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bazel / bazel / c55ec0f2cb3f5b44e5025bf9d3c5dc91d94db287 / . / third_party / grpc / src / core / lib / iomgr / ev_epollex_linux.cc
blob: 4258ded8a04f9c8e195e2e0f5cb208b32064929d [file] [log] [blame]
/*
*
* Copyright 2017 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#include <grpc/support/port_platform.h>
#include "src/core/lib/iomgr/port.h"
#include <grpc/support/log.h>
/* This polling engine is only relevant on linux kernels supporting epoll() */
#ifdef GRPC_LINUX_EPOLL_CREATE1
#include "src/core/lib/iomgr/ev_epollex_linux.h"
#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <poll.h>
#include <pthread.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <grpc/support/alloc.h>
#include <grpc/support/string_util.h>
#include "src/core/lib/debug/stats.h"
#include "src/core/lib/gpr/spinlock.h"
#include "src/core/lib/gpr/tls.h"
#include "src/core/lib/gpr/useful.h"
#include "src/core/lib/gprpp/manual_constructor.h"
#include "src/core/lib/gprpp/mutex_lock.h"
#include "src/core/lib/iomgr/block_annotate.h"
#include "src/core/lib/iomgr/iomgr_internal.h"
#include "src/core/lib/iomgr/is_epollexclusive_available.h"
#include "src/core/lib/iomgr/lockfree_event.h"
#include "src/core/lib/iomgr/sys_epoll_wrapper.h"
#include "src/core/lib/iomgr/timer.h"
#include "src/core/lib/iomgr/wakeup_fd_posix.h"
#include "src/core/lib/profiling/timers.h"
// debug aid: create workers on the heap (allows asan to spot
// use-after-destruction)
//#define GRPC_EPOLLEX_CREATE_WORKERS_ON_HEAP 1
#define MAX_EPOLL_EVENTS 100
// TODO(juanlishen): We use a greater-than-one value here as a workaround fix to
// a keepalive ping timeout issue. We may want to revert https://github
// .com/grpc/grpc/pull/14943 once we figure out the root cause.
#define MAX_EPOLL_EVENTS_HANDLED_EACH_POLL_CALL 16
#define MAX_FDS_IN_CACHE 32
grpc_core::DebugOnlyTraceFlag grpc_trace_pollable_refcount(false,
"pollable_refcount");
/*******************************************************************************
* pollable Declarations
*/
typedef enum { PO_MULTI, PO_FD, PO_EMPTY } pollable_type;
typedef struct pollable pollable;
typedef struct cached_fd {
// Set to the grpc_fd's salt value. See 'salt' variable' in grpc_fd for more
// details
intptr_t salt;
// The underlying fd
int fd;
// A recency time counter that helps to determine the LRU fd in the cache
uint64_t last_used;
} cached_fd;
/// A pollable is something that can be polled: it has an epoll set to poll on,
/// and a wakeup fd for kicks
/// There are three broad types:
/// - PO_EMPTY - the empty pollable, used before file descriptors are added to
/// a pollset
/// - PO_FD - a pollable containing only one FD - used to optimize single-fd
/// pollsets (which are common with synchronous api usage)
/// - PO_MULTI - a pollable containing many fds
struct pollable {
pollable_type type; // immutable
gpr_refcount refs;
int epfd;
grpc_wakeup_fd wakeup;
// The following are relevant only for type PO_FD
grpc_fd* owner_fd; // Set to the owner_fd if the type is PO_FD
gpr_mu owner_orphan_mu; // Synchronizes access to owner_orphaned field
bool owner_orphaned; // Is the owner fd orphaned
grpc_pollset_set* pollset_set;
pollable* next;
pollable* prev;
gpr_mu mu;
grpc_pollset_worker* root_worker;
int event_cursor;
int event_count;
struct epoll_event events[MAX_EPOLL_EVENTS];
// We may be calling pollable_add_fd() on the same (pollable, fd) multiple
// times. To prevent pollable_add_fd() from making multiple sys calls to
// epoll_ctl() to add the fd, we maintain a cache of what fds are already
// present in the underlying epoll-set.
//
// Since this is not a correctness issue, we do not need to maintain all the
// fds in the cache. Hence we just use an LRU cache of size 'MAX_FDS_IN_CACHE'
//
// NOTE: An ideal implementation of this should do the following:
// 1) Add fds to the cache in pollable_add_fd() function (i.e whenever the fd
// is added to the pollable's epoll set)
// 2) Remove the fd from the cache whenever the fd is removed from the
// underlying epoll set (i.e whenever fd_orphan() is called).
//
// Implementing (2) above (i.e removing fds from cache on fd_orphan) adds a
// lot of complexity since an fd can be present in multiple pollables. So our
// implementation ONLY DOES (1) and NOT (2).
//
// The cache_fd.salt variable helps here to maintain correctness (it serves as
// an epoch that differentiates one grpc_fd from the other even though both of
// them may have the same fd number)
//
// The following implements LRU-eviction cache of fds in this pollable
cached_fd fd_cache[MAX_FDS_IN_CACHE];
int fd_cache_size;
uint64_t fd_cache_counter; // Recency timer tick counter
};
static const char* pollable_type_string(pollable_type t) {
switch (t) {
case PO_MULTI:
return "pollset";
case PO_FD:
return "fd";
case PO_EMPTY:
return "empty";
}
return "<invalid>";
}
static char* pollable_desc(pollable* p) {
char* out;
gpr_asprintf(&out, "type=%s epfd=%d wakeup=%d", pollable_type_string(p->type),
p->epfd, p->wakeup.read_fd);
return out;
}
/// Shared empty pollable - used by pollset to poll on until the first fd is
/// added
static pollable* g_empty_pollable;
static grpc_error* pollable_create(pollable_type type, pollable** p);
#ifdef NDEBUG
static pollable* pollable_ref(pollable* p);
static void pollable_unref(pollable* p);
#define POLLABLE_REF(p, r) pollable_ref(p)
#define POLLABLE_UNREF(p, r) pollable_unref(p)
#else
static pollable* pollable_ref(pollable* p, int line, const char* reason);
static void pollable_unref(pollable* p, int line, const char* reason);
#define POLLABLE_REF(p, r) pollable_ref((p), __LINE__, (r))
#define POLLABLE_UNREF(p, r) pollable_unref((p), __LINE__, (r))
#endif
/*******************************************************************************
* Fd Declarations
*/
// Monotonically increasing Epoch counter that is assinged to each grpc_fd. See
// the description of 'salt' variable in 'grpc_fd' for more details
// TODO: (sreek/kpayson) gpr_atm is intptr_t which may not be wide-enough on
// 32-bit systems. Change this to int_64 - atleast on 32-bit systems
static gpr_atm g_fd_salt;
struct grpc_fd {
int fd;
// Since fd numbers can be reused (after old fds are closed), this serves as
// an epoch that uniquely identifies this fd (i.e the pair (salt, fd) is
// unique (until the salt counter (i.e g_fd_salt) overflows)
intptr_t salt;
// refst format:
// bit 0 : 1=Active / 0=Orphaned
// bits 1-n : refcount
// Ref/Unref by two to avoid altering the orphaned bit
gpr_atm refst;
gpr_mu orphan_mu;
gpr_mu pollable_mu;
pollable* pollable_obj;
grpc_core::ManualConstructor<grpc_core::LockfreeEvent> read_closure;
grpc_core::ManualConstructor<grpc_core::LockfreeEvent> write_closure;
grpc_core::ManualConstructor<grpc_core::LockfreeEvent> error_closure;
struct grpc_fd* freelist_next;
grpc_closure* on_done_closure;
grpc_iomgr_object iomgr_object;
// Do we need to track EPOLLERR events separately?
bool track_err;
};
static void fd_global_init(void);
static void fd_global_shutdown(void);
/*******************************************************************************
* Pollset Declarations
*/
typedef struct {
grpc_pollset_worker* next;
grpc_pollset_worker* prev;
} pwlink;
typedef enum { PWLINK_POLLABLE = 0, PWLINK_POLLSET, PWLINK_COUNT } pwlinks;
struct grpc_pollset_worker {
bool kicked;
bool initialized_cv;
#ifndef NDEBUG
// debug aid: which thread started this worker
pid_t originator;
#endif
gpr_cv cv;
grpc_pollset* pollset;
pollable* pollable_obj;
pwlink links[PWLINK_COUNT];
};
struct grpc_pollset {
gpr_mu mu;
gpr_atm worker_count;
pollable* active_pollable;
bool kicked_without_poller;
grpc_closure* shutdown_closure;
bool already_shutdown;
grpc_pollset_worker* root_worker;
int containing_pollset_set_count;
};
/*******************************************************************************
* Pollset-set Declarations
*/
struct grpc_pollset_set {
gpr_refcount refs;
gpr_mu mu;
grpc_pollset_set* parent;
size_t pollset_count;
size_t pollset_capacity;
grpc_pollset** pollsets;
size_t fd_count;
size_t fd_capacity;
grpc_fd** fds;
};
/*******************************************************************************
* Common helpers
*/
static bool append_error(grpc_error** composite, grpc_error* error,
const char* desc) {
if (error == GRPC_ERROR_NONE) return true;
if (*composite == GRPC_ERROR_NONE) {
*composite = GRPC_ERROR_CREATE_FROM_COPIED_STRING(desc);
}
*composite = grpc_error_add_child(*composite, error);
return false;
}
/*******************************************************************************
* Fd Definitions
*/
/* We need to keep a freelist not because of any concerns of malloc performance
* but instead so that implementations with multiple threads in (for example)
* epoll_wait deal with the race between pollset removal and incoming poll
* notifications.
*
* The problem is that the poller ultimately holds a reference to this
* object, so it is very difficult to know when is safe to free it, at least
* without some expensive synchronization.
*
* If we keep the object freelisted, in the worst case losing this race just
* becomes a spurious read notification on a reused fd.
*/
static grpc_fd* fd_freelist = nullptr;
static gpr_mu fd_freelist_mu;
#ifndef NDEBUG
#define REF_BY(fd, n, reason) ref_by(fd, n, reason, __FILE__, __LINE__)
#define UNREF_BY(fd, n, reason) unref_by(fd, n, reason, __FILE__, __LINE__)
static void ref_by(grpc_fd* fd, int n, const char* reason, const char* file,
int line) {
if (grpc_trace_fd_refcount.enabled()) {
gpr_log(GPR_DEBUG,
"FD %d %p ref %d %" PRIdPTR " -> %" PRIdPTR " [%s; %s:%d]",
fd->fd, fd, n, gpr_atm_no_barrier_load(&fd->refst),
gpr_atm_no_barrier_load(&fd->refst) + n, reason, file, line);
}
#else
#define REF_BY(fd, n, reason) ref_by(fd, n)
#define UNREF_BY(fd, n, reason) unref_by(fd, n)
static void ref_by(grpc_fd* fd, int n) {
#endif
GPR_ASSERT(gpr_atm_no_barrier_fetch_add(&fd->refst, n) > 0);
}
#ifndef NDEBUG
#define INVALIDATE_FD(fd) invalidate_fd(fd)
/* Since an fd is never really destroyed (i.e gpr_free() is not called), it is
* hard to cases where fd fields are accessed even after calling fd_destroy().
* The following invalidates fd fields to make catching such errors easier */
static void invalidate_fd(grpc_fd* fd) {
fd->fd = -1;
fd->salt = -1;
gpr_atm_no_barrier_store(&fd->refst, -1);
memset(&fd->orphan_mu, -1, sizeof(fd->orphan_mu));
memset(&fd->pollable_mu, -1, sizeof(fd->pollable_mu));
fd->pollable_obj = nullptr;
fd->on_done_closure = nullptr;
memset(&fd->iomgr_object, -1, sizeof(fd->iomgr_object));
fd->track_err = false;
}
#else
#define INVALIDATE_FD(fd)
#endif
/* Uninitialize and add to the freelist */
static void fd_destroy(void* arg, grpc_error* error) {
grpc_fd* fd = static_cast<grpc_fd*>(arg);
grpc_iomgr_unregister_object(&fd->iomgr_object);
POLLABLE_UNREF(fd->pollable_obj, "fd_pollable");
gpr_mu_destroy(&fd->pollable_mu);
gpr_mu_destroy(&fd->orphan_mu);
fd->read_closure->DestroyEvent();
fd->write_closure->DestroyEvent();
fd->error_closure->DestroyEvent();
INVALIDATE_FD(fd);
/* Add the fd to the freelist */
gpr_mu_lock(&fd_freelist_mu);
fd->freelist_next = fd_freelist;
fd_freelist = fd;
gpr_mu_unlock(&fd_freelist_mu);
}
#ifndef NDEBUG
static void unref_by(grpc_fd* fd, int n, const char* reason, const char* file,
int line) {
if (grpc_trace_fd_refcount.enabled()) {
gpr_log(GPR_DEBUG,
"FD %d %p unref %d %" PRIdPTR " -> %" PRIdPTR " [%s; %s:%d]",
fd->fd, fd, n, gpr_atm_no_barrier_load(&fd->refst),
gpr_atm_no_barrier_load(&fd->refst) - n, reason, file, line);
}
#else
static void unref_by(grpc_fd* fd, int n) {
#endif
gpr_atm old = gpr_atm_full_fetch_add(&fd->refst, -n);
if (old == n) {
GRPC_CLOSURE_SCHED(
GRPC_CLOSURE_CREATE(fd_destroy, fd, grpc_schedule_on_exec_ctx),
GRPC_ERROR_NONE);
} else {
GPR_ASSERT(old > n);
}
}
static void fd_global_init(void) { gpr_mu_init(&fd_freelist_mu); }
static void fd_global_shutdown(void) {
// TODO(guantaol): We don't have a reasonable explanation about this
// lock()/unlock() pattern. It can be a valid barrier if there is at most one
// pending lock() at this point. Otherwise, there is still a possibility of
// use-after-free race. Need to reason about the code and/or clean it up.
gpr_mu_lock(&fd_freelist_mu);
gpr_mu_unlock(&fd_freelist_mu);
while (fd_freelist != nullptr) {
grpc_fd* fd = fd_freelist;
fd_freelist = fd_freelist->freelist_next;
gpr_free(fd);
}
gpr_mu_destroy(&fd_freelist_mu);
}
static grpc_fd* fd_create(int fd, const char* name, bool track_err) {
grpc_fd* new_fd = nullptr;
gpr_mu_lock(&fd_freelist_mu);
if (fd_freelist != nullptr) {
new_fd = fd_freelist;
fd_freelist = fd_freelist->freelist_next;
}
gpr_mu_unlock(&fd_freelist_mu);
if (new_fd == nullptr) {
new_fd = static_cast<grpc_fd*>(gpr_malloc(sizeof(grpc_fd)));
new_fd->read_closure.Init();
new_fd->write_closure.Init();
new_fd->error_closure.Init();
}
new_fd->fd = fd;
new_fd->salt = gpr_atm_no_barrier_fetch_add(&g_fd_salt, 1);
gpr_atm_rel_store(&new_fd->refst, (gpr_atm)1);
gpr_mu_init(&new_fd->orphan_mu);
gpr_mu_init(&new_fd->pollable_mu);
new_fd->pollable_obj = nullptr;
new_fd->read_closure->InitEvent();
new_fd->write_closure->InitEvent();
new_fd->error_closure->InitEvent();
new_fd->freelist_next = nullptr;
new_fd->on_done_closure = nullptr;
char* fd_name;
gpr_asprintf(&fd_name, "%s fd=%d", name, fd);
grpc_iomgr_register_object(&new_fd->iomgr_object, fd_name);
#ifndef NDEBUG
if (grpc_trace_fd_refcount.enabled()) {
gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, new_fd, fd_name);
}
#endif
gpr_free(fd_name);
new_fd->track_err = track_err;
return new_fd;
}
static int fd_wrapped_fd(grpc_fd* fd) {
int ret_fd = fd->fd;
return (gpr_atm_acq_load(&fd->refst) & 1) ? ret_fd : -1;
}
static void fd_orphan(grpc_fd* fd, grpc_closure* on_done, int* release_fd,
const char* reason) {
bool is_fd_closed = false;
gpr_mu_lock(&fd->orphan_mu);
// Get the fd->pollable_obj and set the owner_orphaned on that pollable to
// true so that the pollable will no longer access its owner_fd field.
gpr_mu_lock(&fd->pollable_mu);
pollable* pollable_obj = fd->pollable_obj;
gpr_mu_unlock(&fd->pollable_mu);
if (pollable_obj) {
gpr_mu_lock(&pollable_obj->owner_orphan_mu);
pollable_obj->owner_orphaned = true;
}
fd->on_done_closure = on_done;
/* If release_fd is not NULL, we should be relinquishing control of the file
descriptor fd->fd (but we still own the grpc_fd structure). */
if (release_fd != nullptr) {
*release_fd = fd->fd;
} else {
close(fd->fd);
is_fd_closed = true;
}
// TODO(sreek): handle fd removal (where is_fd_closed=false)
if (!is_fd_closed) {
GRPC_FD_TRACE("epoll_fd %p (%d) was orphaned but not closed.", fd, fd->fd);
}
/* Remove the active status but keep referenced. We want this grpc_fd struct
to be alive (and not added to freelist) until the end of this function */
REF_BY(fd, 1, reason);
GRPC_CLOSURE_SCHED(fd->on_done_closure, GRPC_ERROR_NONE);
if (pollable_obj) {
gpr_mu_unlock(&pollable_obj->owner_orphan_mu);
}
gpr_mu_unlock(&fd->orphan_mu);
UNREF_BY(fd, 2, reason); /* Drop the reference */
}
static bool fd_is_shutdown(grpc_fd* fd) {
return fd->read_closure->IsShutdown();
}
/* Might be called multiple times */
static void fd_shutdown(grpc_fd* fd, grpc_error* why) {
if (fd->read_closure->SetShutdown(GRPC_ERROR_REF(why))) {
if (shutdown(fd->fd, SHUT_RDWR)) {
if (errno != ENOTCONN) {
gpr_log(GPR_ERROR, "Error shutting down fd %d. errno: %d",
grpc_fd_wrapped_fd(fd), errno);
}
}
fd->write_closure->SetShutdown(GRPC_ERROR_REF(why));
fd->error_closure->SetShutdown(GRPC_ERROR_REF(why));
}
GRPC_ERROR_UNREF(why);
}
static void fd_notify_on_read(grpc_fd* fd, grpc_closure* closure) {
fd->read_closure->NotifyOn(closure);
}
static void fd_notify_on_write(grpc_fd* fd, grpc_closure* closure) {
fd->write_closure->NotifyOn(closure);
}
static void fd_notify_on_error(grpc_fd* fd, grpc_closure* closure) {
fd->error_closure->NotifyOn(closure);
}
/*******************************************************************************
* Pollable Definitions
*/
static grpc_error* pollable_create(pollable_type type, pollable** p) {
*p = nullptr;
int epfd = epoll_create1(EPOLL_CLOEXEC);
if (epfd == -1) {
return GRPC_OS_ERROR(errno, "epoll_create1");
}
GRPC_FD_TRACE("Pollable_create: created epfd: %d (type: %d)", epfd, type);
*p = static_cast<pollable*>(gpr_malloc(sizeof(**p)));
grpc_error* err = grpc_wakeup_fd_init(&(*p)->wakeup);
if (err != GRPC_ERROR_NONE) {
GRPC_FD_TRACE(
"Pollable_create: closed epfd: %d (type: %d). wakeupfd_init error",
epfd, type);
close(epfd);
gpr_free(*p);
*p = nullptr;
return err;
}
struct epoll_event ev;
ev.events = static_cast<uint32_t>(EPOLLIN | EPOLLET);
ev.data.ptr = (void*)(1 | (intptr_t) & (*p)->wakeup);
if (epoll_ctl(epfd, EPOLL_CTL_ADD, (*p)->wakeup.read_fd, &ev) != 0) {
err = GRPC_OS_ERROR(errno, "epoll_ctl");
GRPC_FD_TRACE(
"Pollable_create: closed epfd: %d (type: %d). epoll_ctl error", epfd,
type);
close(epfd);
grpc_wakeup_fd_destroy(&(*p)->wakeup);
gpr_free(*p);
*p = nullptr;
return err;
}
(*p)->type = type;
gpr_ref_init(&(*p)->refs, 1);
gpr_mu_init(&(*p)->mu);
(*p)->epfd = epfd;
(*p)->owner_fd = nullptr;
gpr_mu_init(&(*p)->owner_orphan_mu);
(*p)->owner_orphaned = false;
(*p)->pollset_set = nullptr;
(*p)->next = (*p)->prev = *p;
(*p)->root_worker = nullptr;
(*p)->event_cursor = 0;
(*p)->event_count = 0;
(*p)->fd_cache_size = 0;
(*p)->fd_cache_counter = 0;
return GRPC_ERROR_NONE;
}
#ifdef NDEBUG
static pollable* pollable_ref(pollable* p) {
#else
static pollable* pollable_ref(pollable* p, int line, const char* reason) {
if (grpc_trace_pollable_refcount.enabled()) {
int r = static_cast<int> gpr_atm_no_barrier_load(&p->refs.count);
gpr_log(__FILE__, line, GPR_LOG_SEVERITY_DEBUG,
"POLLABLE:%p ref %d->%d %s", p, r, r + 1, reason);
}
#endif
gpr_ref(&p->refs);
return p;
}
#ifdef NDEBUG
static void pollable_unref(pollable* p) {
#else
static void pollable_unref(pollable* p, int line, const char* reason) {
if (p == nullptr) return;
if (grpc_trace_pollable_refcount.enabled()) {
int r = static_cast<int> gpr_atm_no_barrier_load(&p->refs.count);
gpr_log(__FILE__, line, GPR_LOG_SEVERITY_DEBUG,
"POLLABLE:%p unref %d->%d %s", p, r, r - 1, reason);
}
#endif
if (p != nullptr && gpr_unref(&p->refs)) {
GRPC_FD_TRACE("pollable_unref: Closing epfd: %d", p->epfd);
close(p->epfd);
grpc_wakeup_fd_destroy(&p->wakeup);
gpr_mu_destroy(&p->owner_orphan_mu);
gpr_free(p);
}
}
static grpc_error* pollable_add_fd(pollable* p, grpc_fd* fd) {
grpc_error* error = GRPC_ERROR_NONE;
static const char* err_desc = "pollable_add_fd";
const int epfd = p->epfd;
gpr_mu_lock(&p->mu);
p->fd_cache_counter++;
// Handle the case of overflow for our cache counter by
// reseting the recency-counter on all cache objects
if (p->fd_cache_counter == 0) {
for (int i = 0; i < p->fd_cache_size; i++) {
p->fd_cache[i].last_used = 0;
}
}
int lru_idx = 0;
for (int i = 0; i < p->fd_cache_size; i++) {
if (p->fd_cache[i].fd == fd->fd && p->fd_cache[i].salt == fd->salt) {
GRPC_STATS_INC_POLLSET_FD_CACHE_HITS();
p->fd_cache[i].last_used = p->fd_cache_counter;
gpr_mu_unlock(&p->mu);
return GRPC_ERROR_NONE;
} else if (p->fd_cache[i].last_used < p->fd_cache[lru_idx].last_used) {
lru_idx = i;
}
}
// Add to cache
if (p->fd_cache_size < MAX_FDS_IN_CACHE) {
lru_idx = p->fd_cache_size;
p->fd_cache_size++;
}
p->fd_cache[lru_idx].fd = fd->fd;
p->fd_cache[lru_idx].salt = fd->salt;
p->fd_cache[lru_idx].last_used = p->fd_cache_counter;
gpr_mu_unlock(&p->mu);
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "add fd %p (%d) to pollable %p", fd, fd->fd, p);
}
struct epoll_event ev_fd;
ev_fd.events =
static_cast<uint32_t>(EPOLLET | EPOLLIN | EPOLLOUT | EPOLLEXCLUSIVE);
/* Use the second least significant bit of ev_fd.data.ptr to store track_err
* to avoid synchronization issues when accessing it after receiving an event.
* Accessing fd would be a data race there because the fd might have been
* returned to the free list at that point. */
ev_fd.data.ptr = reinterpret_cast<void*>(reinterpret_cast<intptr_t>(fd) |
(fd->track_err ? 2 : 0));
GRPC_STATS_INC_SYSCALL_EPOLL_CTL();
if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd->fd, &ev_fd) != 0) {
switch (errno) {
case EEXIST:
break;
default:
append_error(&error, GRPC_OS_ERROR(errno, "epoll_ctl"), err_desc);
}
}
return error;
}
/*******************************************************************************
* Pollset Definitions
*/
GPR_TLS_DECL(g_current_thread_pollset);
GPR_TLS_DECL(g_current_thread_worker);
/* Global state management */
static grpc_error* pollset_global_init(void) {
gpr_tls_init(&g_current_thread_pollset);
gpr_tls_init(&g_current_thread_worker);
return pollable_create(PO_EMPTY, &g_empty_pollable);
}
static void pollset_global_shutdown(void) {
POLLABLE_UNREF(g_empty_pollable, "g_empty_pollable");
gpr_tls_destroy(&g_current_thread_pollset);
gpr_tls_destroy(&g_current_thread_worker);
}
/* pollset->mu must be held while calling this function */
static void pollset_maybe_finish_shutdown(grpc_pollset* pollset) {
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO,
"PS:%p (pollable:%p) maybe_finish_shutdown sc=%p (target:!NULL) "
"rw=%p (target:NULL) cpsc=%d (target:0)",
pollset, pollset->active_pollable, pollset->shutdown_closure,
pollset->root_worker, pollset->containing_pollset_set_count);
}
if (pollset->shutdown_closure != nullptr && pollset->root_worker == nullptr &&
pollset->containing_pollset_set_count == 0) {
GPR_TIMER_MARK("pollset_finish_shutdown", 0);
GRPC_CLOSURE_SCHED(pollset->shutdown_closure, GRPC_ERROR_NONE);
pollset->shutdown_closure = nullptr;
pollset->already_shutdown = true;
}
}
/* pollset->mu must be held before calling this function,
* pollset->active_pollable->mu & specific_worker->pollable_obj->mu must not be
* held */
static grpc_error* kick_one_worker(grpc_pollset_worker* specific_worker) {
GPR_TIMER_SCOPE("kick_one_worker", 0);
pollable* p = specific_worker->pollable_obj;
grpc_core::MutexLock lock(&p->mu);
GPR_ASSERT(specific_worker != nullptr);
if (specific_worker->kicked) {
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PS:%p kicked_specific_but_already_kicked", p);
}
GRPC_STATS_INC_POLLSET_KICKED_AGAIN();
return GRPC_ERROR_NONE;
}
if (gpr_tls_get(&g_current_thread_worker) == (intptr_t)specific_worker) {
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PS:%p kicked_specific_but_awake", p);
}
GRPC_STATS_INC_POLLSET_KICK_OWN_THREAD();
specific_worker->kicked = true;
return GRPC_ERROR_NONE;
}
if (specific_worker == p->root_worker) {
GRPC_STATS_INC_POLLSET_KICK_WAKEUP_FD();
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PS:%p kicked_specific_via_wakeup_fd", p);
}
specific_worker->kicked = true;
grpc_error* error = grpc_wakeup_fd_wakeup(&p->wakeup);
return error;
}
if (specific_worker->initialized_cv) {
GRPC_STATS_INC_POLLSET_KICK_WAKEUP_CV();
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PS:%p kicked_specific_via_cv", p);
}
specific_worker->kicked = true;
gpr_cv_signal(&specific_worker->cv);
return GRPC_ERROR_NONE;
}
// we can get here during end_worker after removing specific_worker from the
// pollable list but before removing it from the pollset list
return GRPC_ERROR_NONE;
}
static grpc_error* pollset_kick(grpc_pollset* pollset,
grpc_pollset_worker* specific_worker) {
GPR_TIMER_SCOPE("pollset_kick", 0);
GRPC_STATS_INC_POLLSET_KICK();
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO,
"PS:%p kick %p tls_pollset=%p tls_worker=%p pollset.root_worker=%p",
pollset, specific_worker,
(void*)gpr_tls_get(&g_current_thread_pollset),
(void*)gpr_tls_get(&g_current_thread_worker), pollset->root_worker);
}
if (specific_worker == nullptr) {
if (gpr_tls_get(&g_current_thread_pollset) != (intptr_t)pollset) {
if (pollset->root_worker == nullptr) {
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PS:%p kicked_any_without_poller", pollset);
}
GRPC_STATS_INC_POLLSET_KICKED_WITHOUT_POLLER();
pollset->kicked_without_poller = true;
return GRPC_ERROR_NONE;
} else {
// We've been asked to kick a poller, but we haven't been told which one
// ... any will do
// We look at the pollset worker list because:
// 1. the pollable list may include workers from other pollers, so we'd
// need to do an O(N) search
// 2. we'd additionally need to take the pollable lock, which we've so
// far avoided
// Now, we would prefer to wake a poller in cv_wait, and not in
// epoll_wait (since the latter would imply the need to do an additional
// wakeup)
// We know that if a worker is at the root of a pollable, it's (likely)
// also the root of a pollset, and we know that if a worker is NOT at
// the root of a pollset, it's (likely) not at the root of a pollable,
// so we take our chances and choose the SECOND worker enqueued against
// the pollset as a worker that's likely to be in cv_wait
return kick_one_worker(
pollset->root_worker->links[PWLINK_POLLSET].next);
}
} else {
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PS:%p kicked_any_but_awake", pollset);
}
GRPC_STATS_INC_POLLSET_KICK_OWN_THREAD();
return GRPC_ERROR_NONE;
}
} else {
return kick_one_worker(specific_worker);
}
}
static grpc_error* pollset_kick_all(grpc_pollset* pollset) {
GPR_TIMER_SCOPE("pollset_kick_all", 0);
grpc_error* error = GRPC_ERROR_NONE;
const char* err_desc = "pollset_kick_all";
grpc_pollset_worker* w = pollset->root_worker;
if (w != nullptr) {
do {
GRPC_STATS_INC_POLLSET_KICK();
append_error(&error, kick_one_worker(w), err_desc);
w = w->links[PWLINK_POLLSET].next;
} while (w != pollset->root_worker);
}
return error;
}
static void pollset_init(grpc_pollset* pollset, gpr_mu** mu) {
gpr_mu_init(&pollset->mu);
gpr_atm_no_barrier_store(&pollset->worker_count, 0);
pollset->active_pollable = POLLABLE_REF(g_empty_pollable, "pollset");
pollset->kicked_without_poller = false;
pollset->shutdown_closure = nullptr;
pollset->already_shutdown = false;
pollset->root_worker = nullptr;
pollset->containing_pollset_set_count = 0;
*mu = &pollset->mu;
}
static int poll_deadline_to_millis_timeout(grpc_millis millis) {
if (millis == GRPC_MILLIS_INF_FUTURE) return -1;
grpc_millis delta = millis - grpc_core::ExecCtx::Get()->Now();
if (delta > INT_MAX)
return INT_MAX;
else if (delta < 0)
return 0;
else
return static_cast<int>(delta);
}
static void fd_become_readable(grpc_fd* fd) { fd->read_closure->SetReady(); }
static void fd_become_writable(grpc_fd* fd) { fd->write_closure->SetReady(); }
static void fd_has_errors(grpc_fd* fd) { fd->error_closure->SetReady(); }
/* Get the pollable_obj attached to this fd. If none is attached, create a new
* pollable object (of type PO_FD), attach it to the fd and return it
*
* Note that if a pollable object is already attached to the fd, it may be of
* either PO_FD or PO_MULTI type */
static grpc_error* get_fd_pollable(grpc_fd* fd, pollable** p) {
gpr_mu_lock(&fd->pollable_mu);
grpc_error* error = GRPC_ERROR_NONE;
static const char* err_desc = "get_fd_pollable";
if (fd->pollable_obj == nullptr) {
if (append_error(&error, pollable_create(PO_FD, &fd->pollable_obj),
err_desc)) {
fd->pollable_obj->owner_fd = fd;
if (!append_error(&error, pollable_add_fd(fd->pollable_obj, fd),
err_desc)) {
POLLABLE_UNREF(fd->pollable_obj, "fd_pollable");
fd->pollable_obj = nullptr;
}
}
}
if (error == GRPC_ERROR_NONE) {
GPR_ASSERT(fd->pollable_obj != nullptr);
*p = POLLABLE_REF(fd->pollable_obj, "pollset");
} else {
GPR_ASSERT(fd->pollable_obj == nullptr);
*p = nullptr;
}
gpr_mu_unlock(&fd->pollable_mu);
return error;
}
/* pollset->po.mu lock must be held by the caller before calling this */
static void pollset_shutdown(grpc_pollset* pollset, grpc_closure* closure) {
GPR_TIMER_SCOPE("pollset_shutdown", 0);
GPR_ASSERT(pollset->shutdown_closure == nullptr);
pollset->shutdown_closure = closure;
GRPC_LOG_IF_ERROR("pollset_shutdown", pollset_kick_all(pollset));
pollset_maybe_finish_shutdown(pollset);
}
static grpc_error* pollable_process_events(grpc_pollset* pollset,
pollable* pollable_obj, bool drain) {
GPR_TIMER_SCOPE("pollable_process_events", 0);
static const char* err_desc = "pollset_process_events";
// Use a simple heuristic to determine how many fd events to process
// per loop iteration. (events/workers)
int handle_count = 1;
int worker_count = gpr_atm_no_barrier_load(&pollset->worker_count);
GPR_ASSERT(worker_count > 0);
handle_count =
(pollable_obj->event_count - pollable_obj->event_cursor) / worker_count;
if (handle_count == 0) {
handle_count = 1;
} else if (handle_count > MAX_EPOLL_EVENTS_HANDLED_EACH_POLL_CALL) {
handle_count = MAX_EPOLL_EVENTS_HANDLED_EACH_POLL_CALL;
}
grpc_error* error = GRPC_ERROR_NONE;
for (int i = 0; (drain || i < handle_count) &&
pollable_obj->event_cursor != pollable_obj->event_count;
i++) {
int n = pollable_obj->event_cursor++;
struct epoll_event* ev = &pollable_obj->events[n];
void* data_ptr = ev->data.ptr;
if (1 & (intptr_t)data_ptr) {
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PS:%p got pollset_wakeup %p", pollset, data_ptr);
}
append_error(&error,
grpc_wakeup_fd_consume_wakeup(
(grpc_wakeup_fd*)((~static_cast<intptr_t>(1)) &
(intptr_t)data_ptr)),
err_desc);
} else {
grpc_fd* fd =
reinterpret_cast<grpc_fd*>(reinterpret_cast<intptr_t>(data_ptr) & ~2);
bool track_err = reinterpret_cast<intptr_t>(data_ptr) & 2;
bool cancel = (ev->events & EPOLLHUP) != 0;
bool error = (ev->events & EPOLLERR) != 0;
bool read_ev = (ev->events & (EPOLLIN | EPOLLPRI)) != 0;
bool write_ev = (ev->events & EPOLLOUT) != 0;
bool err_fallback = error && !track_err;
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO,
"PS:%p got fd %p: cancel=%d read=%d "
"write=%d",
pollset, fd, cancel, read_ev, write_ev);
}
if (error && !err_fallback) {
fd_has_errors(fd);
}
if (read_ev || cancel || err_fallback) {
fd_become_readable(fd);
}
if (write_ev || cancel || err_fallback) {
fd_become_writable(fd);
}
}
}
return error;
}
/* pollset_shutdown is guaranteed to be called before pollset_destroy. */
static void pollset_destroy(grpc_pollset* pollset) {
POLLABLE_UNREF(pollset->active_pollable, "pollset");
pollset->active_pollable = nullptr;
gpr_mu_destroy(&pollset->mu);
}
static grpc_error* pollable_epoll(pollable* p, grpc_millis deadline) {
GPR_TIMER_SCOPE("pollable_epoll", 0);
int timeout = poll_deadline_to_millis_timeout(deadline);
if (grpc_polling_trace.enabled()) {
char* desc = pollable_desc(p);
gpr_log(GPR_INFO, "POLLABLE:%p[%s] poll for %dms", p, desc, timeout);
gpr_free(desc);
}
if (timeout != 0) {
GRPC_SCHEDULING_START_BLOCKING_REGION;
}
int r;
do {
GRPC_STATS_INC_SYSCALL_POLL();
r = epoll_wait(p->epfd, p->events, MAX_EPOLL_EVENTS, timeout);
} while (r < 0 && errno == EINTR);
if (timeout != 0) {
GRPC_SCHEDULING_END_BLOCKING_REGION;
}
if (r < 0) return GRPC_OS_ERROR(errno, "epoll_wait");
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "POLLABLE:%p got %d events", p, r);
}
p->event_cursor = 0;
p->event_count = r;
return GRPC_ERROR_NONE;
}
/* Return true if first in list */
static bool worker_insert(grpc_pollset_worker** root_worker,
grpc_pollset_worker* worker, pwlinks link) {
if (*root_worker == nullptr) {
*root_worker = worker;
worker->links[link].next = worker->links[link].prev = worker;
return true;
} else {
worker->links[link].next = *root_worker;
worker->links[link].prev = worker->links[link].next->links[link].prev;
worker->links[link].next->links[link].prev = worker;
worker->links[link].prev->links[link].next = worker;
return false;
}
}
/* returns the new root IFF the root changed */
typedef enum { WRR_NEW_ROOT, WRR_EMPTIED, WRR_REMOVED } worker_remove_result;
static worker_remove_result worker_remove(grpc_pollset_worker** root_worker,
grpc_pollset_worker* worker,
pwlinks link) {
if (worker == *root_worker) {
if (worker == worker->links[link].next) {
*root_worker = nullptr;
return WRR_EMPTIED;
} else {
*root_worker = worker->links[link].next;
worker->links[link].prev->links[link].next = worker->links[link].next;
worker->links[link].next->links[link].prev = worker->links[link].prev;
return WRR_NEW_ROOT;
}
} else {
worker->links[link].prev->links[link].next = worker->links[link].next;
worker->links[link].next->links[link].prev = worker->links[link].prev;
return WRR_REMOVED;
}
}
/* Return true if this thread should poll */
static bool begin_worker(grpc_pollset* pollset, grpc_pollset_worker* worker,
grpc_pollset_worker** worker_hdl,
grpc_millis deadline) {
GPR_TIMER_SCOPE("begin_worker", 0);
bool do_poll =
(pollset->shutdown_closure == nullptr && !pollset->already_shutdown);
gpr_atm_no_barrier_fetch_add(&pollset->worker_count, 1);
if (worker_hdl != nullptr) *worker_hdl = worker;
worker->initialized_cv = false;
worker->kicked = false;
worker->pollset = pollset;
worker->pollable_obj =
POLLABLE_REF(pollset->active_pollable, "pollset_worker");
worker_insert(&pollset->root_worker, worker, PWLINK_POLLSET);
gpr_mu_lock(&worker->pollable_obj->mu);
if (!worker_insert(&worker->pollable_obj->root_worker, worker,
PWLINK_POLLABLE)) {
worker->initialized_cv = true;
gpr_cv_init(&worker->cv);
gpr_mu_unlock(&pollset->mu);
if (grpc_polling_trace.enabled() &&
worker->pollable_obj->root_worker != worker) {
gpr_log(GPR_INFO, "PS:%p wait %p w=%p for %dms", pollset,
worker->pollable_obj, worker,
poll_deadline_to_millis_timeout(deadline));
}
while (do_poll && worker->pollable_obj->root_worker != worker) {
if (gpr_cv_wait(&worker->cv, &worker->pollable_obj->mu,
grpc_millis_to_timespec(deadline, GPR_CLOCK_REALTIME))) {
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PS:%p timeout_wait %p w=%p", pollset,
worker->pollable_obj, worker);
}
do_poll = false;
} else if (worker->kicked) {
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PS:%p wakeup %p w=%p", pollset,
worker->pollable_obj, worker);
}
do_poll = false;
} else if (grpc_polling_trace.enabled() &&
worker->pollable_obj->root_worker != worker) {
gpr_log(GPR_INFO, "PS:%p spurious_wakeup %p w=%p", pollset,
worker->pollable_obj, worker);
}
}
grpc_core::ExecCtx::Get()->InvalidateNow();
} else {
gpr_mu_unlock(&pollset->mu);
}
gpr_mu_unlock(&worker->pollable_obj->mu);
return do_poll;
}
static void end_worker(grpc_pollset* pollset, grpc_pollset_worker* worker,
grpc_pollset_worker** worker_hdl) {
GPR_TIMER_SCOPE("end_worker", 0);
gpr_mu_lock(&pollset->mu);
gpr_mu_lock(&worker->pollable_obj->mu);
switch (worker_remove(&worker->pollable_obj->root_worker, worker,
PWLINK_POLLABLE)) {
case WRR_NEW_ROOT: {
// wakeup new poller
grpc_pollset_worker* new_root = worker->pollable_obj->root_worker;
GPR_ASSERT(new_root->initialized_cv);
gpr_cv_signal(&new_root->cv);
break;
}
case WRR_EMPTIED:
if (pollset->active_pollable != worker->pollable_obj) {
// pollable no longer being polled: flush events
pollable_process_events(pollset, worker->pollable_obj, true);
}
break;
case WRR_REMOVED:
break;
}
gpr_mu_unlock(&worker->pollable_obj->mu);
POLLABLE_UNREF(worker->pollable_obj, "pollset_worker");
if (worker_remove(&pollset->root_worker, worker, PWLINK_POLLSET) ==
WRR_EMPTIED) {
pollset_maybe_finish_shutdown(pollset);
}
if (worker->initialized_cv) {
gpr_cv_destroy(&worker->cv);
}
gpr_atm_no_barrier_fetch_add(&pollset->worker_count, -1);
}
#ifndef NDEBUG
static long sys_gettid(void) { return syscall(__NR_gettid); }
#endif
/* pollset->mu lock must be held by the caller before calling this.
The function pollset_work() may temporarily release the lock (pollset->po.mu)
during the course of its execution but it will always re-acquire the lock and
ensure that it is held by the time the function returns */
static grpc_error* pollset_work(grpc_pollset* pollset,
grpc_pollset_worker** worker_hdl,
grpc_millis deadline) {
GPR_TIMER_SCOPE("pollset_work", 0);
#ifdef GRPC_EPOLLEX_CREATE_WORKERS_ON_HEAP
grpc_pollset_worker* worker =
(grpc_pollset_worker*)gpr_malloc(sizeof(*worker));
#define WORKER_PTR (worker)
#else
grpc_pollset_worker worker;
#define WORKER_PTR (&worker)
#endif
#ifndef NDEBUG
WORKER_PTR->originator = sys_gettid();
#endif
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO,
"PS:%p work hdl=%p worker=%p now=%" PRId64 " deadline=%" PRId64
" kwp=%d pollable=%p",
pollset, worker_hdl, WORKER_PTR, grpc_core::ExecCtx::Get()->Now(),
deadline, pollset->kicked_without_poller, pollset->active_pollable);
}
static const char* err_desc = "pollset_work";
grpc_error* error = GRPC_ERROR_NONE;
if (pollset->kicked_without_poller) {
pollset->kicked_without_poller = false;
} else {
if (begin_worker(pollset, WORKER_PTR, worker_hdl, deadline)) {
gpr_tls_set(&g_current_thread_pollset, (intptr_t)pollset);
gpr_tls_set(&g_current_thread_worker, (intptr_t)WORKER_PTR);
if (WORKER_PTR->pollable_obj->event_cursor ==
WORKER_PTR->pollable_obj->event_count) {
append_error(&error, pollable_epoll(WORKER_PTR->pollable_obj, deadline),
err_desc);
}
append_error(
&error,
pollable_process_events(pollset, WORKER_PTR->pollable_obj, false),
err_desc);
grpc_core::ExecCtx::Get()->Flush();
gpr_tls_set(&g_current_thread_pollset, 0);
gpr_tls_set(&g_current_thread_worker, 0);
}
end_worker(pollset, WORKER_PTR, worker_hdl);
}
#ifdef GRPC_EPOLLEX_CREATE_WORKERS_ON_HEAP
gpr_free(worker);
#endif
#undef WORKER_PTR
return error;
}
static grpc_error* pollset_transition_pollable_from_empty_to_fd_locked(
grpc_pollset* pollset, grpc_fd* fd) {
static const char* err_desc = "pollset_transition_pollable_from_empty_to_fd";
grpc_error* error = GRPC_ERROR_NONE;
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO,
"PS:%p add fd %p (%d); transition pollable from empty to fd",
pollset, fd, fd->fd);
}
append_error(&error, pollset_kick_all(pollset), err_desc);
POLLABLE_UNREF(pollset->active_pollable, "pollset");
append_error(&error, get_fd_pollable(fd, &pollset->active_pollable),
err_desc);
return error;
}
static grpc_error* pollset_transition_pollable_from_fd_to_multi_locked(
grpc_pollset* pollset, grpc_fd* and_add_fd) {
static const char* err_desc = "pollset_transition_pollable_from_fd_to_multi";
grpc_error* error = GRPC_ERROR_NONE;
if (grpc_polling_trace.enabled()) {
gpr_log(
GPR_INFO,
"PS:%p add fd %p (%d); transition pollable from fd %p to multipoller",
pollset, and_add_fd, and_add_fd ? and_add_fd->fd : -1,
pollset->active_pollable->owner_fd);
}
append_error(&error, pollset_kick_all(pollset), err_desc);
grpc_fd* initial_fd = pollset->active_pollable->owner_fd;
POLLABLE_UNREF(pollset->active_pollable, "pollset");
pollset->active_pollable = nullptr;
if (append_error(&error, pollable_create(PO_MULTI, &pollset->active_pollable),
err_desc)) {
append_error(&error, pollable_add_fd(pollset->active_pollable, initial_fd),
err_desc);
if (and_add_fd != nullptr) {
append_error(&error,
pollable_add_fd(pollset->active_pollable, and_add_fd),
err_desc);
}
}
return error;
}
/* expects pollsets locked, flag whether fd is locked or not */
static grpc_error* pollset_add_fd_locked(grpc_pollset* pollset, grpc_fd* fd) {
grpc_error* error = GRPC_ERROR_NONE;
pollable* po_at_start =
POLLABLE_REF(pollset->active_pollable, "pollset_add_fd");
switch (pollset->active_pollable->type) {
case PO_EMPTY:
/* empty pollable --> single fd pollable */
error = pollset_transition_pollable_from_empty_to_fd_locked(pollset, fd);
break;
case PO_FD:
gpr_mu_lock(&po_at_start->owner_orphan_mu);
if (po_at_start->owner_orphaned) {
error =
pollset_transition_pollable_from_empty_to_fd_locked(pollset, fd);
} else {
/* fd --> multipoller */
error =
pollset_transition_pollable_from_fd_to_multi_locked(pollset, fd);
}
gpr_mu_unlock(&po_at_start->owner_orphan_mu);
break;
case PO_MULTI:
error = pollable_add_fd(pollset->active_pollable, fd);
break;
}
if (error != GRPC_ERROR_NONE) {
POLLABLE_UNREF(pollset->active_pollable, "pollset");
pollset->active_pollable = po_at_start;
} else {
POLLABLE_UNREF(po_at_start, "pollset_add_fd");
}
return error;
}
static grpc_error* pollset_as_multipollable_locked(grpc_pollset* pollset,
pollable** pollable_obj) {
grpc_error* error = GRPC_ERROR_NONE;
pollable* po_at_start =
POLLABLE_REF(pollset->active_pollable, "pollset_as_multipollable");
switch (pollset->active_pollable->type) {
case PO_EMPTY:
POLLABLE_UNREF(pollset->active_pollable, "pollset");
error = pollable_create(PO_MULTI, &pollset->active_pollable);
/* Any workers currently polling on this pollset must now be woked up so
* that they can pick up the new active_pollable */
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO,
"PS:%p active pollable transition from empty to multi",
pollset);
}
static const char* err_desc =
"pollset_as_multipollable_locked: empty -> multi";
append_error(&error, pollset_kick_all(pollset), err_desc);
break;
case PO_FD:
gpr_mu_lock(&po_at_start->owner_orphan_mu);
if (po_at_start->owner_orphaned) {
// Unlock before Unref'ing the pollable
gpr_mu_unlock(&po_at_start->owner_orphan_mu);
POLLABLE_UNREF(pollset->active_pollable, "pollset");
error = pollable_create(PO_MULTI, &pollset->active_pollable);
} else {
error = pollset_transition_pollable_from_fd_to_multi_locked(pollset,
nullptr);
gpr_mu_unlock(&po_at_start->owner_orphan_mu);
}
break;
case PO_MULTI:
break;
}
if (error != GRPC_ERROR_NONE) {
POLLABLE_UNREF(pollset->active_pollable, "pollset");
pollset->active_pollable = po_at_start;
*pollable_obj = nullptr;
} else {
*pollable_obj = POLLABLE_REF(pollset->active_pollable, "pollset_set");
POLLABLE_UNREF(po_at_start, "pollset_as_multipollable");
}
return error;
}
static void pollset_add_fd(grpc_pollset* pollset, grpc_fd* fd) {
GPR_TIMER_SCOPE("pollset_add_fd", 0);
gpr_mu_lock(&pollset->mu);
grpc_error* error = pollset_add_fd_locked(pollset, fd);
gpr_mu_unlock(&pollset->mu);
GRPC_LOG_IF_ERROR("pollset_add_fd", error);
}
/*******************************************************************************
* Pollset-set Definitions
*/
static grpc_pollset_set* pss_lock_adam(grpc_pollset_set* pss) {
gpr_mu_lock(&pss->mu);
while (pss->parent != nullptr) {
gpr_mu_unlock(&pss->mu);
pss = pss->parent;
gpr_mu_lock(&pss->mu);
}
return pss;
}
static grpc_pollset_set* pollset_set_create(void) {
grpc_pollset_set* pss =
static_cast<grpc_pollset_set*>(gpr_zalloc(sizeof(*pss)));
gpr_mu_init(&pss->mu);
gpr_ref_init(&pss->refs, 1);
return pss;
}
static void pollset_set_unref(grpc_pollset_set* pss) {
if (pss == nullptr) return;
if (!gpr_unref(&pss->refs)) return;
pollset_set_unref(pss->parent);
gpr_mu_destroy(&pss->mu);
for (size_t i = 0; i < pss->pollset_count; i++) {
gpr_mu_lock(&pss->pollsets[i]->mu);
if (0 == --pss->pollsets[i]->containing_pollset_set_count) {
pollset_maybe_finish_shutdown(pss->pollsets[i]);
}
gpr_mu_unlock(&pss->pollsets[i]->mu);
}
for (size_t i = 0; i < pss->fd_count; i++) {
UNREF_BY(pss->fds[i], 2, "pollset_set");
}
gpr_free(pss->pollsets);
gpr_free(pss->fds);
gpr_free(pss);
}
static void pollset_set_add_fd(grpc_pollset_set* pss, grpc_fd* fd) {
GPR_TIMER_SCOPE("pollset_set_add_fd", 0);
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PSS:%p: add fd %p (%d)", pss, fd, fd->fd);
}
grpc_error* error = GRPC_ERROR_NONE;
static const char* err_desc = "pollset_set_add_fd";
pss = pss_lock_adam(pss);
for (size_t i = 0; i < pss->pollset_count; i++) {
append_error(&error, pollable_add_fd(pss->pollsets[i]->active_pollable, fd),
err_desc);
}
if (pss->fd_count == pss->fd_capacity) {
pss->fd_capacity = GPR_MAX(pss->fd_capacity * 2, 8);
pss->fds = static_cast<grpc_fd**>(
gpr_realloc(pss->fds, pss->fd_capacity * sizeof(*pss->fds)));
}
REF_BY(fd, 2, "pollset_set");
pss->fds[pss->fd_count++] = fd;
gpr_mu_unlock(&pss->mu);
GRPC_LOG_IF_ERROR(err_desc, error);
}
static void pollset_set_del_fd(grpc_pollset_set* pss, grpc_fd* fd) {
GPR_TIMER_SCOPE("pollset_set_del_fd", 0);
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PSS:%p: del fd %p", pss, fd);
}
pss = pss_lock_adam(pss);
size_t i;
for (i = 0; i < pss->fd_count; i++) {
if (pss->fds[i] == fd) {
UNREF_BY(fd, 2, "pollset_set");
break;
}
}
GPR_ASSERT(i != pss->fd_count);
for (; i < pss->fd_count - 1; i++) {
pss->fds[i] = pss->fds[i + 1];
}
pss->fd_count--;
gpr_mu_unlock(&pss->mu);
}
static void pollset_set_del_pollset(grpc_pollset_set* pss, grpc_pollset* ps) {
GPR_TIMER_SCOPE("pollset_set_del_pollset", 0);
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PSS:%p: del pollset %p", pss, ps);
}
pss = pss_lock_adam(pss);
size_t i;
for (i = 0; i < pss->pollset_count; i++) {
if (pss->pollsets[i] == ps) {
break;
}
}
GPR_ASSERT(i != pss->pollset_count);
for (; i < pss->pollset_count - 1; i++) {
pss->pollsets[i] = pss->pollsets[i + 1];
}
pss->pollset_count--;
gpr_mu_unlock(&pss->mu);
gpr_mu_lock(&ps->mu);
if (0 == --ps->containing_pollset_set_count) {
pollset_maybe_finish_shutdown(ps);
}
gpr_mu_unlock(&ps->mu);
}
// add all fds to pollables, and output a new array of unorphaned out_fds
// assumes pollsets are multipollable
static grpc_error* add_fds_to_pollsets(grpc_fd** fds, size_t fd_count,
grpc_pollset** pollsets,
size_t pollset_count,
const char* err_desc, grpc_fd** out_fds,
size_t* out_fd_count) {
GPR_TIMER_SCOPE("add_fds_to_pollsets", 0);
grpc_error* error = GRPC_ERROR_NONE;
for (size_t i = 0; i < fd_count; i++) {
gpr_mu_lock(&fds[i]->orphan_mu);
if ((gpr_atm_no_barrier_load(&fds[i]->refst) & 1) == 0) {
gpr_mu_unlock(&fds[i]->orphan_mu);
UNREF_BY(fds[i], 2, "pollset_set");
} else {
for (size_t j = 0; j < pollset_count; j++) {
append_error(&error,
pollable_add_fd(pollsets[j]->active_pollable, fds[i]),
err_desc);
}
gpr_mu_unlock(&fds[i]->orphan_mu);
out_fds[(*out_fd_count)++] = fds[i];
}
}
return error;
}
static void pollset_set_add_pollset(grpc_pollset_set* pss, grpc_pollset* ps) {
GPR_TIMER_SCOPE("pollset_set_add_pollset", 0);
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PSS:%p: add pollset %p", pss, ps);
}
grpc_error* error = GRPC_ERROR_NONE;
static const char* err_desc = "pollset_set_add_pollset";
pollable* pollable_obj = nullptr;
gpr_mu_lock(&ps->mu);
if (!GRPC_LOG_IF_ERROR(err_desc,
pollset_as_multipollable_locked(ps, &pollable_obj))) {
GPR_ASSERT(pollable_obj == nullptr);
gpr_mu_unlock(&ps->mu);
return;
}
ps->containing_pollset_set_count++;
gpr_mu_unlock(&ps->mu);
pss = pss_lock_adam(pss);
size_t initial_fd_count = pss->fd_count;
pss->fd_count = 0;
append_error(&error,
add_fds_to_pollsets(pss->fds, initial_fd_count, &ps, 1, err_desc,
pss->fds, &pss->fd_count),
err_desc);
if (pss->pollset_count == pss->pollset_capacity) {
pss->pollset_capacity = GPR_MAX(pss->pollset_capacity * 2, 8);
pss->pollsets = static_cast<grpc_pollset**>(gpr_realloc(
pss->pollsets, pss->pollset_capacity * sizeof(*pss->pollsets)));
}
pss->pollsets[pss->pollset_count++] = ps;
gpr_mu_unlock(&pss->mu);
POLLABLE_UNREF(pollable_obj, "pollset_set");
GRPC_LOG_IF_ERROR(err_desc, error);
}
static void pollset_set_add_pollset_set(grpc_pollset_set* a,
grpc_pollset_set* b) {
GPR_TIMER_SCOPE("pollset_set_add_pollset_set", 0);
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PSS: merge (%p, %p)", a, b);
}
grpc_error* error = GRPC_ERROR_NONE;
static const char* err_desc = "pollset_set_add_fd";
for (;;) {
if (a == b) {
// pollset ancestors are the same: nothing to do
return;
}
if (a > b) {
GPR_SWAP(grpc_pollset_set*, a, b);
}
gpr_mu* a_mu = &a->mu;
gpr_mu* b_mu = &b->mu;
gpr_mu_lock(a_mu);
gpr_mu_lock(b_mu);
if (a->parent != nullptr) {
a = a->parent;
} else if (b->parent != nullptr) {
b = b->parent;
} else {
break; // exit loop, both pollsets locked
}
gpr_mu_unlock(a_mu);
gpr_mu_unlock(b_mu);
}
// try to do the least copying possible
// TODO(sreek): there's probably a better heuristic here
const size_t a_size = a->fd_count + a->pollset_count;
const size_t b_size = b->fd_count + b->pollset_count;
if (b_size > a_size) {
GPR_SWAP(grpc_pollset_set*, a, b);
}
if (grpc_polling_trace.enabled()) {
gpr_log(GPR_INFO, "PSS: parent %p to %p", b, a);
}
gpr_ref(&a->refs);
b->parent = a;
if (a->fd_capacity < a->fd_count + b->fd_count) {
a->fd_capacity = GPR_MAX(2 * a->fd_capacity, a->fd_count + b->fd_count);
a->fds = static_cast<grpc_fd**>(
gpr_realloc(a->fds, a->fd_capacity * sizeof(*a->fds)));
}
size_t initial_a_fd_count = a->fd_count;
a->fd_count = 0;
append_error(
&error,
add_fds_to_pollsets(a->fds, initial_a_fd_count, b->pollsets,
b->pollset_count, "merge_a2b", a->fds, &a->fd_count),
err_desc);
append_error(
&error,
add_fds_to_pollsets(b->fds, b->fd_count, a->pollsets, a->pollset_count,
"merge_b2a", a->fds, &a->fd_count),
err_desc);
if (a->pollset_capacity < a->pollset_count + b->pollset_count) {
a->pollset_capacity =
GPR_MAX(2 * a->pollset_capacity, a->pollset_count + b->pollset_count);
a->pollsets = static_cast<grpc_pollset**>(
gpr_realloc(a->pollsets, a->pollset_capacity * sizeof(*a->pollsets)));
}
if (b->pollset_count > 0) {
memcpy(a->pollsets + a->pollset_count, b->pollsets,
b->pollset_count * sizeof(*b->pollsets));
}
a->pollset_count += b->pollset_count;
gpr_free(b->fds);
gpr_free(b->pollsets);
b->fds = nullptr;
b->pollsets = nullptr;
b->fd_count = b->fd_capacity = b->pollset_count = b->pollset_capacity = 0;
gpr_mu_unlock(&a->mu);
gpr_mu_unlock(&b->mu);
}
static void pollset_set_del_pollset_set(grpc_pollset_set* bag,
grpc_pollset_set* item) {}
/*******************************************************************************
* Event engine binding
*/
static void shutdown_background_closure(void) {}
static void shutdown_engine(void) {
fd_global_shutdown();
pollset_global_shutdown();
}
static const grpc_event_engine_vtable vtable = {
sizeof(grpc_pollset),
true,
false,
fd_create,
fd_wrapped_fd,
fd_orphan,
fd_shutdown,
fd_notify_on_read,
fd_notify_on_write,
fd_notify_on_error,
fd_become_readable,
fd_become_writable,
fd_has_errors,
fd_is_shutdown,
pollset_init,
pollset_shutdown,
pollset_destroy,
pollset_work,
pollset_kick,
pollset_add_fd,
pollset_set_create,
pollset_set_unref, // destroy ==> unref 1 public ref
pollset_set_add_pollset,
pollset_set_del_pollset,
pollset_set_add_pollset_set,
pollset_set_del_pollset_set,
pollset_set_add_fd,
pollset_set_del_fd,
shutdown_background_closure,
shutdown_engine,
};
const grpc_event_engine_vtable* grpc_init_epollex_linux(
bool explicitly_requested) {
if (!grpc_has_wakeup_fd()) {
gpr_log(GPR_ERROR, "Skipping epollex because of no wakeup fd.");
return nullptr;
}
if (!grpc_is_epollexclusive_available()) {
gpr_log(GPR_INFO, "Skipping epollex because it is not supported.");
return nullptr;
}
fd_global_init();
if (!GRPC_LOG_IF_ERROR("pollset_global_init", pollset_global_init())) {
pollset_global_shutdown();
fd_global_shutdown();
return nullptr;
}
return &vtable;
}
#else /* defined(GRPC_LINUX_EPOLL_CREATE1) */
#if defined(GRPC_POSIX_SOCKET_EV_EPOLLEX)
#include "src/core/lib/iomgr/ev_epollex_linux.h"
/* If GRPC_LINUX_EPOLL_CREATE1 is not defined, it means
epoll_create1 is not available. Return NULL */
const grpc_event_engine_vtable* grpc_init_epollex_linux(
bool explicitly_requested) {
return nullptr;
}
#endif /* defined(GRPC_POSIX_SOCKET_EV_EPOLLEX) */
#endif /* !defined(GRPC_LINUX_EPOLL_CREATE1) */