diff options
Diffstat (limited to 'src/core/lib/iomgr/ev_epoll1_linux.c')
| -rw-r--r-- | src/core/lib/iomgr/ev_epoll1_linux.c | 984 |
1 files changed, 984 insertions, 0 deletions
diff --git a/src/core/lib/iomgr/ev_epoll1_linux.c b/src/core/lib/iomgr/ev_epoll1_linux.c new file mode 100644 index 0000000000..ad69f808cd --- /dev/null +++ b/src/core/lib/iomgr/ev_epoll1_linux.c @@ -0,0 +1,984 @@ +/* + * + * Copyright 2017, Google Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * * Neither the name of Google Inc. nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + */ + +#include "src/core/lib/iomgr/port.h" + +/* This polling engine is only relevant on linux kernels supporting epoll() */ +#ifdef GRPC_LINUX_EPOLL + +#include "src/core/lib/iomgr/ev_epoll1_linux.h" + +#include <assert.h> +#include <errno.h> +#include <poll.h> +#include <pthread.h> +#include <string.h> +#include <sys/epoll.h> +#include <sys/socket.h> +#include <unistd.h> + +#include <grpc/support/alloc.h> +#include <grpc/support/cpu.h> +#include <grpc/support/log.h> +#include <grpc/support/string_util.h> +#include <grpc/support/tls.h> +#include <grpc/support/useful.h> + +#include "src/core/lib/iomgr/ev_posix.h" +#include "src/core/lib/iomgr/iomgr_internal.h" +#include "src/core/lib/iomgr/lockfree_event.h" +#include "src/core/lib/iomgr/wakeup_fd_posix.h" +#include "src/core/lib/iomgr/workqueue.h" +#include "src/core/lib/profiling/timers.h" +#include "src/core/lib/support/block_annotate.h" + +static grpc_wakeup_fd global_wakeup_fd; +static int g_epfd; + +/******************************************************************************* + * Fd Declarations + */ + +struct grpc_fd { + int fd; + + gpr_atm read_closure; + gpr_atm write_closure; + + struct grpc_fd *freelist_next; + + /* The pollset that last noticed that the fd is readable. The actual type + * stored in this is (grpc_pollset *) */ + gpr_atm read_notifier_pollset; + + grpc_iomgr_object iomgr_object; +}; + +static void fd_global_init(void); +static void fd_global_shutdown(void); + +/******************************************************************************* + * Pollset Declarations + */ + +typedef enum { UNKICKED, KICKED, DESIGNATED_POLLER } kick_state; + +struct grpc_pollset_worker { + kick_state kick_state; + bool initialized_cv; + grpc_pollset_worker *next; + grpc_pollset_worker *prev; + gpr_cv cv; + grpc_closure_list schedule_on_end_work; +}; + +#define MAX_NEIGHBOURHOODS 1024 + +typedef struct pollset_neighbourhood { + gpr_mu mu; + grpc_pollset *active_root; + char pad[GPR_CACHELINE_SIZE]; +} pollset_neighbourhood; + +struct grpc_pollset { + gpr_mu mu; + pollset_neighbourhood *neighbourhood; + bool reassigning_neighbourhood; + grpc_pollset_worker *root_worker; + bool kicked_without_poller; + bool seen_inactive; + bool shutting_down; /* Is the pollset shutting down ? */ + bool finish_shutdown_called; /* Is the 'finish_shutdown_locked()' called ? */ + grpc_closure *shutdown_closure; /* Called after after shutdown is complete */ + int begin_refs; + + grpc_pollset *next; + grpc_pollset *prev; +}; + +/******************************************************************************* + * Pollset-set Declarations + */ + +struct grpc_pollset_set {}; + +/******************************************************************************* + * 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. + */ + +/* The alarm system needs to be able to wakeup 'some poller' sometimes + * (specifically when a new alarm needs to be triggered earlier than the next + * alarm 'epoch'). This wakeup_fd gives us something to alert on when such a + * case occurs. */ + +static grpc_fd *fd_freelist = NULL; +static gpr_mu fd_freelist_mu; + +static void fd_global_init(void) { gpr_mu_init(&fd_freelist_mu); } + +static void fd_global_shutdown(void) { + gpr_mu_lock(&fd_freelist_mu); + gpr_mu_unlock(&fd_freelist_mu); + while (fd_freelist != NULL) { + 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) { + grpc_fd *new_fd = NULL; + + gpr_mu_lock(&fd_freelist_mu); + if (fd_freelist != NULL) { + new_fd = fd_freelist; + fd_freelist = fd_freelist->freelist_next; + } + gpr_mu_unlock(&fd_freelist_mu); + + if (new_fd == NULL) { + new_fd = gpr_malloc(sizeof(grpc_fd)); + } + + new_fd->fd = fd; + grpc_lfev_init(&new_fd->read_closure); + grpc_lfev_init(&new_fd->write_closure); + gpr_atm_no_barrier_store(&new_fd->read_notifier_pollset, (gpr_atm)NULL); + + new_fd->freelist_next = NULL; + + char *fd_name; + gpr_asprintf(&fd_name, "%s fd=%d", name, fd); + grpc_iomgr_register_object(&new_fd->iomgr_object, fd_name); +#ifdef GRPC_FD_REF_COUNT_DEBUG + gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, (void *)new_fd, fd_name); +#endif + gpr_free(fd_name); + + struct epoll_event ev = {.events = (uint32_t)(EPOLLIN | EPOLLOUT | EPOLLET), + .data.ptr = new_fd}; + if (epoll_ctl(g_epfd, EPOLL_CTL_ADD, fd, &ev) != 0) { + gpr_log(GPR_ERROR, "epoll_ctl failed: %s", strerror(errno)); + } + + return new_fd; +} + +static int fd_wrapped_fd(grpc_fd *fd) { return fd->fd; } + +/* Might be called multiple times */ +static void fd_shutdown(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_error *why) { + if (grpc_lfev_set_shutdown(exec_ctx, &fd->read_closure, + GRPC_ERROR_REF(why))) { + shutdown(fd->fd, SHUT_RDWR); + grpc_lfev_set_shutdown(exec_ctx, &fd->write_closure, GRPC_ERROR_REF(why)); + } + GRPC_ERROR_UNREF(why); +} + +static void fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, + grpc_closure *on_done, int *release_fd, + const char *reason) { + grpc_error *error = GRPC_ERROR_NONE; + + if (!grpc_lfev_is_shutdown(&fd->read_closure)) { + fd_shutdown(exec_ctx, fd, GRPC_ERROR_CREATE_FROM_COPIED_STRING(reason)); + } + + /* 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 != NULL) { + *release_fd = fd->fd; + } else { + close(fd->fd); + } + + grpc_closure_sched(exec_ctx, on_done, GRPC_ERROR_REF(error)); + + grpc_iomgr_unregister_object(&fd->iomgr_object); + grpc_lfev_destroy(&fd->read_closure); + grpc_lfev_destroy(&fd->write_closure); + + gpr_mu_lock(&fd_freelist_mu); + fd->freelist_next = fd_freelist; + fd_freelist = fd; + gpr_mu_unlock(&fd_freelist_mu); +} + +static grpc_pollset *fd_get_read_notifier_pollset(grpc_exec_ctx *exec_ctx, + grpc_fd *fd) { + gpr_atm notifier = gpr_atm_acq_load(&fd->read_notifier_pollset); + return (grpc_pollset *)notifier; +} + +static bool fd_is_shutdown(grpc_fd *fd) { + return grpc_lfev_is_shutdown(&fd->read_closure); +} + +static void fd_notify_on_read(grpc_exec_ctx *exec_ctx, grpc_fd *fd, + grpc_closure *closure) { + grpc_lfev_notify_on(exec_ctx, &fd->read_closure, closure); +} + +static void fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd, + grpc_closure *closure) { + grpc_lfev_notify_on(exec_ctx, &fd->write_closure, closure); +} + +static grpc_workqueue *fd_get_workqueue(grpc_fd *fd) { + return (grpc_workqueue *)0xb0b51ed; +} + +static void fd_become_readable(grpc_exec_ctx *exec_ctx, grpc_fd *fd, + grpc_pollset *notifier) { + grpc_lfev_set_ready(exec_ctx, &fd->read_closure); + + /* Note, it is possible that fd_become_readable might be called twice with + different 'notifier's when an fd becomes readable and it is in two epoll + sets (This can happen briefly during polling island merges). In such cases + it does not really matter which notifer is set as the read_notifier_pollset + (They would both point to the same polling island anyway) */ + /* Use release store to match with acquire load in fd_get_read_notifier */ + gpr_atm_rel_store(&fd->read_notifier_pollset, (gpr_atm)notifier); +} + +static void fd_become_writable(grpc_exec_ctx *exec_ctx, grpc_fd *fd) { + grpc_lfev_set_ready(exec_ctx, &fd->write_closure); +} + +/******************************************************************************* + * Pollset Definitions + */ + +GPR_TLS_DECL(g_current_thread_pollset); +GPR_TLS_DECL(g_current_thread_worker); +static gpr_atm g_active_poller; +static pollset_neighbourhood *g_neighbourhoods; +static size_t g_num_neighbourhoods; +static gpr_mu g_wq_mu; +static grpc_closure_list g_wq_items; + +/* Return true if first in list */ +static bool worker_insert(grpc_pollset *pollset, grpc_pollset_worker *worker) { + if (pollset->root_worker == NULL) { + pollset->root_worker = worker; + worker->next = worker->prev = worker; + return true; + } else { + worker->next = pollset->root_worker; + worker->prev = worker->next->prev; + worker->next->prev = worker; + worker->prev->next = worker; + return false; + } +} + +/* Return true if last in list */ +typedef enum { EMPTIED, NEW_ROOT, REMOVED } worker_remove_result; + +static worker_remove_result worker_remove(grpc_pollset *pollset, + grpc_pollset_worker *worker) { + if (worker == pollset->root_worker) { + if (worker == worker->next) { + pollset->root_worker = NULL; + return EMPTIED; + } else { + pollset->root_worker = worker->next; + worker->prev->next = worker->next; + worker->next->prev = worker->prev; + return NEW_ROOT; + } + } else { + worker->prev->next = worker->next; + worker->next->prev = worker->prev; + return REMOVED; + } +} + +static size_t choose_neighbourhood(void) { + return (size_t)gpr_cpu_current_cpu() % g_num_neighbourhoods; +} + +static grpc_error *pollset_global_init(void) { + gpr_tls_init(&g_current_thread_pollset); + gpr_tls_init(&g_current_thread_worker); + gpr_atm_no_barrier_store(&g_active_poller, 0); + global_wakeup_fd.read_fd = -1; + grpc_error *err = grpc_wakeup_fd_init(&global_wakeup_fd); + gpr_mu_init(&g_wq_mu); + g_wq_items = (grpc_closure_list)GRPC_CLOSURE_LIST_INIT; + if (err != GRPC_ERROR_NONE) return err; + struct epoll_event ev = {.events = (uint32_t)(EPOLLIN | EPOLLET), + .data.ptr = &global_wakeup_fd}; + if (epoll_ctl(g_epfd, EPOLL_CTL_ADD, global_wakeup_fd.read_fd, &ev) != 0) { + return GRPC_OS_ERROR(errno, "epoll_ctl"); + } + g_num_neighbourhoods = GPR_CLAMP(gpr_cpu_num_cores(), 1, MAX_NEIGHBOURHOODS); + g_neighbourhoods = + gpr_zalloc(sizeof(*g_neighbourhoods) * g_num_neighbourhoods); + for (size_t i = 0; i < g_num_neighbourhoods; i++) { + gpr_mu_init(&g_neighbourhoods[i].mu); + } + return GRPC_ERROR_NONE; +} + +static void pollset_global_shutdown(void) { + gpr_tls_destroy(&g_current_thread_pollset); + gpr_tls_destroy(&g_current_thread_worker); + gpr_mu_destroy(&g_wq_mu); + if (global_wakeup_fd.read_fd != -1) grpc_wakeup_fd_destroy(&global_wakeup_fd); + for (size_t i = 0; i < g_num_neighbourhoods; i++) { + gpr_mu_destroy(&g_neighbourhoods[i].mu); + } + gpr_free(g_neighbourhoods); +} + +static void pollset_init(grpc_pollset *pollset, gpr_mu **mu) { + gpr_mu_init(&pollset->mu); + *mu = &pollset->mu; + pollset->neighbourhood = &g_neighbourhoods[choose_neighbourhood()]; + pollset->seen_inactive = true; +} + +static void pollset_destroy(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset) { + gpr_mu_lock(&pollset->mu); + if (!pollset->seen_inactive) { + pollset_neighbourhood *neighbourhood = pollset->neighbourhood; + gpr_mu_unlock(&pollset->mu); + retry_lock_neighbourhood: + gpr_mu_lock(&neighbourhood->mu); + gpr_mu_lock(&pollset->mu); + if (!pollset->seen_inactive) { + if (pollset->neighbourhood != neighbourhood) { + gpr_mu_unlock(&neighbourhood->mu); + neighbourhood = pollset->neighbourhood; + gpr_mu_unlock(&pollset->mu); + goto retry_lock_neighbourhood; + } + pollset->prev->next = pollset->next; + pollset->next->prev = pollset->prev; + if (pollset == pollset->neighbourhood->active_root) { + pollset->neighbourhood->active_root = + pollset->next == pollset ? NULL : pollset->next; + } + } + gpr_mu_unlock(&pollset->neighbourhood->mu); + } + gpr_mu_unlock(&pollset->mu); + gpr_mu_destroy(&pollset->mu); +} + +static grpc_error *pollset_kick_all(grpc_pollset *pollset) { + grpc_error *error = GRPC_ERROR_NONE; + if (pollset->root_worker != NULL) { + grpc_pollset_worker *worker = pollset->root_worker; + do { + if (worker->initialized_cv) { + worker->kick_state = KICKED; + gpr_cv_signal(&worker->cv); + } else { + worker->kick_state = KICKED; + append_error(&error, grpc_wakeup_fd_wakeup(&global_wakeup_fd), + "pollset_shutdown"); + } + + worker = worker->next; + } while (worker != pollset->root_worker); + } + return error; +} + +static void pollset_maybe_finish_shutdown(grpc_exec_ctx *exec_ctx, + grpc_pollset *pollset) { + if (pollset->shutdown_closure != NULL && pollset->root_worker == NULL && + pollset->begin_refs == 0) { + grpc_closure_sched(exec_ctx, pollset->shutdown_closure, GRPC_ERROR_NONE); + pollset->shutdown_closure = NULL; + } +} + +static void pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, + grpc_closure *closure) { + GPR_ASSERT(pollset->shutdown_closure == NULL); + pollset->shutdown_closure = closure; + GRPC_LOG_IF_ERROR("pollset_shutdown", pollset_kick_all(pollset)); + pollset_maybe_finish_shutdown(exec_ctx, pollset); +} + +#define MAX_EPOLL_EVENTS 100 + +static int poll_deadline_to_millis_timeout(gpr_timespec deadline, + gpr_timespec now) { + gpr_timespec timeout; + if (gpr_time_cmp(deadline, gpr_inf_future(deadline.clock_type)) == 0) { + return -1; + } + + if (gpr_time_cmp(deadline, now) <= 0) { + return 0; + } + + static const gpr_timespec round_up = { + .clock_type = GPR_TIMESPAN, .tv_sec = 0, .tv_nsec = GPR_NS_PER_MS - 1}; + timeout = gpr_time_sub(deadline, now); + int millis = gpr_time_to_millis(gpr_time_add(timeout, round_up)); + return millis >= 1 ? millis : 1; +} + +static grpc_error *pollset_epoll(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, + gpr_timespec now, gpr_timespec deadline) { + struct epoll_event events[MAX_EPOLL_EVENTS]; + static const char *err_desc = "pollset_poll"; + + int timeout = poll_deadline_to_millis_timeout(deadline, now); + + if (timeout != 0) { + GRPC_SCHEDULING_START_BLOCKING_REGION; + } + int r; + do { + r = epoll_wait(g_epfd, 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"); + + grpc_error *error = GRPC_ERROR_NONE; + for (int i = 0; i < r; i++) { + void *data_ptr = events[i].data.ptr; + if (data_ptr == &global_wakeup_fd) { + gpr_mu_lock(&g_wq_mu); + grpc_closure_list_move(&g_wq_items, &exec_ctx->closure_list); + gpr_mu_unlock(&g_wq_mu); + append_error(&error, grpc_wakeup_fd_consume_wakeup(&global_wakeup_fd), + err_desc); + } else { + grpc_fd *fd = (grpc_fd *)(data_ptr); + bool cancel = (events[i].events & (EPOLLERR | EPOLLHUP)) != 0; + bool read_ev = (events[i].events & (EPOLLIN | EPOLLPRI)) != 0; + bool write_ev = (events[i].events & EPOLLOUT) != 0; + if (read_ev || cancel) { + fd_become_readable(exec_ctx, fd, pollset); + } + if (write_ev || cancel) { + fd_become_writable(exec_ctx, fd); + } + } + } + + return error; +} + +static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker, + grpc_pollset_worker **worker_hdl, gpr_timespec *now, + gpr_timespec deadline) { + if (worker_hdl != NULL) *worker_hdl = worker; + worker->initialized_cv = false; + worker->kick_state = UNKICKED; + worker->schedule_on_end_work = (grpc_closure_list)GRPC_CLOSURE_LIST_INIT; + pollset->begin_refs++; + + if (pollset->seen_inactive) { + // pollset has been observed to be inactive, we need to move back to the + // active list + bool is_reassigning = false; + if (!pollset->reassigning_neighbourhood) { + is_reassigning = true; + pollset->reassigning_neighbourhood = true; + pollset->neighbourhood = &g_neighbourhoods[choose_neighbourhood()]; + } + pollset_neighbourhood *neighbourhood = pollset->neighbourhood; + gpr_mu_unlock(&pollset->mu); + // pollset unlocked: state may change (even worker->kick_state) + retry_lock_neighbourhood: + gpr_mu_lock(&neighbourhood->mu); + gpr_mu_lock(&pollset->mu); + if (pollset->seen_inactive) { + if (neighbourhood != pollset->neighbourhood) { + gpr_mu_unlock(&neighbourhood->mu); + neighbourhood = pollset->neighbourhood; + gpr_mu_unlock(&pollset->mu); + goto retry_lock_neighbourhood; + } + pollset->seen_inactive = false; + if (neighbourhood->active_root == NULL) { + neighbourhood->active_root = pollset->next = pollset->prev = pollset; + if (gpr_atm_no_barrier_cas(&g_active_poller, 0, (gpr_atm)worker)) { + worker->kick_state = DESIGNATED_POLLER; + } + } else { + pollset->next = neighbourhood->active_root; + pollset->prev = pollset->next->prev; + pollset->next->prev = pollset->prev->next = pollset; + } + } + if (is_reassigning) { + GPR_ASSERT(pollset->reassigning_neighbourhood); + pollset->reassigning_neighbourhood = false; + } + gpr_mu_unlock(&neighbourhood->mu); + } + worker_insert(pollset, worker); + pollset->begin_refs--; + if (worker->kick_state == UNKICKED) { + GPR_ASSERT(gpr_atm_no_barrier_load(&g_active_poller) != (gpr_atm)worker); + worker->initialized_cv = true; + gpr_cv_init(&worker->cv); + while (worker->kick_state == UNKICKED && + pollset->shutdown_closure == NULL) { + if (gpr_cv_wait(&worker->cv, &pollset->mu, deadline) && + worker->kick_state == UNKICKED) { + worker->kick_state = KICKED; + } + } + *now = gpr_now(now->clock_type); + } + + return worker->kick_state == DESIGNATED_POLLER && + pollset->shutdown_closure == NULL; +} + +static bool check_neighbourhood_for_available_poller( + pollset_neighbourhood *neighbourhood) { + bool found_worker = false; + do { + grpc_pollset *inspect = neighbourhood->active_root; + if (inspect == NULL) { + break; + } + gpr_mu_lock(&inspect->mu); + GPR_ASSERT(!inspect->seen_inactive); + grpc_pollset_worker *inspect_worker = inspect->root_worker; + if (inspect_worker != NULL) { + do { + switch (inspect_worker->kick_state) { + case UNKICKED: + if (gpr_atm_no_barrier_cas(&g_active_poller, 0, + (gpr_atm)inspect_worker)) { + inspect_worker->kick_state = DESIGNATED_POLLER; + if (inspect_worker->initialized_cv) { + gpr_cv_signal(&inspect_worker->cv); + } + } + // even if we didn't win the cas, there's a worker, we can stop + found_worker = true; + break; + case KICKED: + break; + case DESIGNATED_POLLER: + found_worker = true; // ok, so someone else found the worker, but + // we'll accept that + break; + } + inspect_worker = inspect_worker->next; + } while (inspect_worker != inspect->root_worker); + } + if (!found_worker) { + inspect->seen_inactive = true; + if (inspect == neighbourhood->active_root) { + neighbourhood->active_root = + inspect->next == inspect ? NULL : inspect->next; + } + inspect->next->prev = inspect->prev; + inspect->prev->next = inspect->next; + inspect->next = inspect->prev = NULL; + } + gpr_mu_unlock(&inspect->mu); + } while (!found_worker); + return found_worker; +} + +static void end_worker(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, + grpc_pollset_worker *worker, + grpc_pollset_worker **worker_hdl) { + if (worker_hdl != NULL) *worker_hdl = NULL; + worker->kick_state = KICKED; + grpc_closure_list_move(&worker->schedule_on_end_work, + &exec_ctx->closure_list); + if (gpr_atm_no_barrier_load(&g_active_poller) == (gpr_atm)worker) { + if (worker->next != worker && worker->next->kick_state == UNKICKED) { + GPR_ASSERT(worker->next->initialized_cv); + gpr_atm_no_barrier_store(&g_active_poller, (gpr_atm)worker->next); + worker->next->kick_state = DESIGNATED_POLLER; + gpr_cv_signal(&worker->next->cv); + if (grpc_exec_ctx_has_work(exec_ctx)) { + gpr_mu_unlock(&pollset->mu); + grpc_exec_ctx_flush(exec_ctx); + gpr_mu_lock(&pollset->mu); + } + } else { + gpr_atm_no_barrier_store(&g_active_poller, 0); + gpr_mu_unlock(&pollset->mu); + size_t poller_neighbourhood_idx = + (size_t)(pollset->neighbourhood - g_neighbourhoods); + bool found_worker = false; + bool scan_state[MAX_NEIGHBOURHOODS]; + for (size_t i = 0; !found_worker && i < g_num_neighbourhoods; i++) { + pollset_neighbourhood *neighbourhood = + &g_neighbourhoods[(poller_neighbourhood_idx + i) % + g_num_neighbourhoods]; + if (gpr_mu_trylock(&neighbourhood->mu)) { + found_worker = + check_neighbourhood_for_available_poller(neighbourhood); + gpr_mu_unlock(&neighbourhood->mu); + scan_state[i] = true; + } else { + scan_state[i] = false; + } + } + for (size_t i = 0; !found_worker && i < g_num_neighbourhoods; i++) { + if (scan_state[i]) continue; + pollset_neighbourhood *neighbourhood = + &g_neighbourhoods[(poller_neighbourhood_idx + i) % + g_num_neighbourhoods]; + gpr_mu_lock(&neighbourhood->mu); + found_worker = check_neighbourhood_for_available_poller(neighbourhood); + gpr_mu_unlock(&neighbourhood->mu); + } + grpc_exec_ctx_flush(exec_ctx); + gpr_mu_lock(&pollset->mu); + } + } else if (grpc_exec_ctx_has_work(exec_ctx)) { + gpr_mu_unlock(&pollset->mu); + grpc_exec_ctx_flush(exec_ctx); + gpr_mu_lock(&pollset->mu); + } + if (worker->initialized_cv) { + gpr_cv_destroy(&worker->cv); + } + if (EMPTIED == worker_remove(pollset, worker)) { + pollset_maybe_finish_shutdown(exec_ctx, pollset); + } + GPR_ASSERT(gpr_atm_no_barrier_load(&g_active_poller) != (gpr_atm)worker); +} + +/* pollset->po.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_exec_ctx *exec_ctx, grpc_pollset *pollset, + grpc_pollset_worker **worker_hdl, + gpr_timespec now, gpr_timespec deadline) { + grpc_pollset_worker worker; + grpc_error *error = GRPC_ERROR_NONE; + static const char *err_desc = "pollset_work"; + if (pollset->kicked_without_poller) { + pollset->kicked_without_poller = false; + return GRPC_ERROR_NONE; + } + gpr_tls_set(&g_current_thread_pollset, (intptr_t)pollset); + if (begin_worker(pollset, &worker, worker_hdl, &now, deadline)) { + gpr_tls_set(&g_current_thread_worker, (intptr_t)&worker); + GPR_ASSERT(!pollset->shutdown_closure); + GPR_ASSERT(!pollset->seen_inactive); + gpr_mu_unlock(&pollset->mu); + append_error(&error, pollset_epoll(exec_ctx, pollset, now, deadline), + err_desc); + gpr_mu_lock(&pollset->mu); + gpr_tls_set(&g_current_thread_worker, 0); + } + end_worker(exec_ctx, pollset, &worker, worker_hdl); + gpr_tls_set(&g_current_thread_pollset, 0); + return error; +} + +static grpc_error *pollset_kick(grpc_pollset *pollset, + grpc_pollset_worker *specific_worker) { + if (specific_worker == NULL) { + if (gpr_tls_get(&g_current_thread_pollset) != (intptr_t)pollset) { + grpc_pollset_worker *root_worker = pollset->root_worker; + if (root_worker == NULL) { + pollset->kicked_without_poller = true; + return GRPC_ERROR_NONE; + } + grpc_pollset_worker *next_worker = root_worker->next; + if (root_worker == next_worker && + root_worker == (grpc_pollset_worker *)gpr_atm_no_barrier_load( + &g_active_poller)) { + root_worker->kick_state = KICKED; + return grpc_wakeup_fd_wakeup(&global_wakeup_fd); + } else if (next_worker->kick_state == UNKICKED) { + GPR_ASSERT(next_worker->initialized_cv); + next_worker->kick_state = KICKED; + gpr_cv_signal(&next_worker->cv); + return GRPC_ERROR_NONE; + } else { + return GRPC_ERROR_NONE; + } + } else { + return GRPC_ERROR_NONE; + } + } else if (specific_worker->kick_state == KICKED) { + return GRPC_ERROR_NONE; + } else if (gpr_tls_get(&g_current_thread_worker) == + (intptr_t)specific_worker) { + specific_worker->kick_state = KICKED; + return GRPC_ERROR_NONE; + } else if (specific_worker == + (grpc_pollset_worker *)gpr_atm_no_barrier_load(&g_active_poller)) { + specific_worker->kick_state = KICKED; + return grpc_wakeup_fd_wakeup(&global_wakeup_fd); + } else if (specific_worker->initialized_cv) { + specific_worker->kick_state = KICKED; + gpr_cv_signal(&specific_worker->cv); + return GRPC_ERROR_NONE; + } else { + specific_worker->kick_state = KICKED; + return GRPC_ERROR_NONE; + } +} + +static void pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, + grpc_fd *fd) {} + +/******************************************************************************* + * Workqueue Definitions + */ + +#ifdef GRPC_WORKQUEUE_REFCOUNT_DEBUG +static grpc_workqueue *workqueue_ref(grpc_workqueue *workqueue, + const char *file, int line, + const char *reason) { + return workqueue; +} + +static void workqueue_unref(grpc_exec_ctx *exec_ctx, grpc_workqueue *workqueue, + const char *file, int line, const char *reason) {} +#else +static grpc_workqueue *workqueue_ref(grpc_workqueue *workqueue) { + return workqueue; +} + +static void workqueue_unref(grpc_exec_ctx *exec_ctx, + grpc_workqueue *workqueue) {} +#endif + +static void wq_sched(grpc_exec_ctx *exec_ctx, grpc_closure *closure, + grpc_error *error) { + // find a neighbourhood to wakeup + bool scheduled = false; + size_t initial_neighbourhood = choose_neighbourhood(); + for (size_t i = 0; !scheduled && i < g_num_neighbourhoods; i++) { + pollset_neighbourhood *neighbourhood = + &g_neighbourhoods[(initial_neighbourhood + i) % g_num_neighbourhoods]; + if (gpr_mu_trylock(&neighbourhood->mu)) { + if (neighbourhood->active_root != NULL) { + grpc_pollset *inspect = neighbourhood->active_root; + do { + if (gpr_mu_trylock(&inspect->mu)) { + if (inspect->root_worker != NULL) { + grpc_pollset_worker *inspect_worker = inspect->root_worker; + do { + if (inspect_worker->kick_state == UNKICKED) { + inspect_worker->kick_state = KICKED; + grpc_closure_list_append( + &inspect_worker->schedule_on_end_work, closure, error); + if (inspect_worker->initialized_cv) { + gpr_cv_signal(&inspect_worker->cv); + } + scheduled = true; + } + inspect_worker = inspect_worker->next; + } while (!scheduled && inspect_worker != inspect->root_worker); + } + gpr_mu_unlock(&inspect->mu); + } + inspect = inspect->next; + } while (!scheduled && inspect != neighbourhood->active_root); + } + gpr_mu_unlock(&neighbourhood->mu); + } + } + if (!scheduled) { + gpr_mu_lock(&g_wq_mu); + grpc_closure_list_append(&g_wq_items, closure, error); + gpr_mu_unlock(&g_wq_mu); + GRPC_LOG_IF_ERROR("workqueue_scheduler", + grpc_wakeup_fd_wakeup(&global_wakeup_fd)); + } +} + +static const grpc_closure_scheduler_vtable + singleton_workqueue_scheduler_vtable = {wq_sched, wq_sched, + "epoll1_workqueue"}; + +static grpc_closure_scheduler singleton_workqueue_scheduler = { + &singleton_workqueue_scheduler_vtable}; + +static grpc_closure_scheduler *workqueue_scheduler(grpc_workqueue *workqueue) { + return &singleton_workqueue_scheduler; +} + +/******************************************************************************* + * Pollset-set Definitions + */ + +static grpc_pollset_set *pollset_set_create(void) { + return (grpc_pollset_set *)((intptr_t)0xdeafbeef); +} + +static void pollset_set_destroy(grpc_exec_ctx *exec_ctx, + grpc_pollset_set *pss) {} + +static void pollset_set_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset_set *pss, + grpc_fd *fd) {} + +static void pollset_set_del_fd(grpc_exec_ctx *exec_ctx, grpc_pollset_set *pss, + grpc_fd *fd) {} + +static void pollset_set_add_pollset(grpc_exec_ctx *exec_ctx, + grpc_pollset_set *pss, grpc_pollset *ps) {} + +static void pollset_set_del_pollset(grpc_exec_ctx *exec_ctx, + grpc_pollset_set *pss, grpc_pollset *ps) {} + +static void pollset_set_add_pollset_set(grpc_exec_ctx *exec_ctx, + grpc_pollset_set *bag, + grpc_pollset_set *item) {} + +static void pollset_set_del_pollset_set(grpc_exec_ctx *exec_ctx, + grpc_pollset_set *bag, + grpc_pollset_set *item) {} + +/******************************************************************************* + * Event engine binding + */ + +static void shutdown_engine(void) { + fd_global_shutdown(); + pollset_global_shutdown(); +} + +static const grpc_event_engine_vtable vtable = { + .pollset_size = sizeof(grpc_pollset), + + .fd_create = fd_create, + .fd_wrapped_fd = fd_wrapped_fd, + .fd_orphan = fd_orphan, + .fd_shutdown = fd_shutdown, + .fd_is_shutdown = fd_is_shutdown, + .fd_notify_on_read = fd_notify_on_read, + .fd_notify_on_write = fd_notify_on_write, + .fd_get_read_notifier_pollset = fd_get_read_notifier_pollset, + .fd_get_workqueue = fd_get_workqueue, + + .pollset_init = pollset_init, + .pollset_shutdown = pollset_shutdown, + .pollset_destroy = pollset_destroy, + .pollset_work = pollset_work, + .pollset_kick = pollset_kick, + .pollset_add_fd = pollset_add_fd, + + .pollset_set_create = pollset_set_create, + .pollset_set_destroy = pollset_set_destroy, + .pollset_set_add_pollset = pollset_set_add_pollset, + .pollset_set_del_pollset = pollset_set_del_pollset, + .pollset_set_add_pollset_set = pollset_set_add_pollset_set, + .pollset_set_del_pollset_set = pollset_set_del_pollset_set, + .pollset_set_add_fd = pollset_set_add_fd, + .pollset_set_del_fd = pollset_set_del_fd, + + .workqueue_ref = workqueue_ref, + .workqueue_unref = workqueue_unref, + .workqueue_scheduler = workqueue_scheduler, + + .shutdown_engine = shutdown_engine, +}; + +/* It is possible that GLIBC has epoll but the underlying kernel doesn't. + * Create a dummy epoll_fd to make sure epoll support is available */ +const grpc_event_engine_vtable *grpc_init_epoll1_linux(bool explicit_request) { + /* TODO(ctiller): temporary, until this stabilizes */ + if (!explicit_request) return NULL; + + if (!grpc_has_wakeup_fd()) { + return NULL; + } + + g_epfd = epoll_create1(EPOLL_CLOEXEC); + if (g_epfd < 0) { + gpr_log(GPR_ERROR, "epoll unavailable"); + return NULL; + } + + fd_global_init(); + + if (!GRPC_LOG_IF_ERROR("pollset_global_init", pollset_global_init())) { + close(g_epfd); + fd_global_shutdown(); + return NULL; + } + + return &vtable; +} + +#else /* defined(GRPC_LINUX_EPOLL) */ +#if defined(GRPC_POSIX_SOCKET) +#include "src/core/lib/iomgr/ev_posix.h" +/* If GRPC_LINUX_EPOLL is not defined, it means epoll is not available. Return + * NULL */ +const grpc_event_engine_vtable *grpc_init_epoll1_linux(bool explicit_request) { + return NULL; +} +#endif /* defined(GRPC_POSIX_SOCKET) */ +#endif /* !defined(GRPC_LINUX_EPOLL) */ |