diff options
Diffstat (limited to 'src/core/lib/iomgr/ev_epoll1_linux.c')
| -rw-r--r-- | src/core/lib/iomgr/ev_epoll1_linux.c | 286 |
1 files changed, 237 insertions, 49 deletions
diff --git a/src/core/lib/iomgr/ev_epoll1_linux.c b/src/core/lib/iomgr/ev_epoll1_linux.c index 66ba601adb..8db4a92453 100644 --- a/src/core/lib/iomgr/ev_epoll1_linux.c +++ b/src/core/lib/iomgr/ev_epoll1_linux.c @@ -45,6 +45,7 @@ #include "src/core/lib/iomgr/wakeup_fd_posix.h" #include "src/core/lib/profiling/timers.h" #include "src/core/lib/support/block_annotate.h" +#include "src/core/lib/support/string.h" static grpc_wakeup_fd global_wakeup_fd; static int g_epfd; @@ -77,8 +78,21 @@ static void fd_global_shutdown(void); typedef enum { UNKICKED, KICKED, DESIGNATED_POLLER } kick_state; +static const char *kick_state_string(kick_state st) { + switch (st) { + case UNKICKED: + return "UNKICKED"; + case KICKED: + return "KICKED"; + case DESIGNATED_POLLER: + return "DESIGNATED_POLLER"; + } + GPR_UNREACHABLE_CODE(return "UNKNOWN"); +} + struct grpc_pollset_worker { kick_state kick_state; + int kick_state_mutator; // which line of code last changed kick state bool initialized_cv; grpc_pollset_worker *next; grpc_pollset_worker *prev; @@ -86,6 +100,12 @@ struct grpc_pollset_worker { grpc_closure_list schedule_on_end_work; }; +#define SET_KICK_STATE(worker, state) \ + do { \ + (worker)->kick_state = (state); \ + (worker)->kick_state_mutator = __LINE__; \ + } while (false) + #define MAX_NEIGHBOURHOODS 1024 typedef struct pollset_neighbourhood { @@ -100,10 +120,15 @@ struct grpc_pollset { bool reassigning_neighbourhood; grpc_pollset_worker *root_worker; bool kicked_without_poller; + + /* Set to true if the pollset is observed to have no workers available to + * poll */ bool seen_inactive; - bool shutting_down; /* Is the pollset shutting down ? */ - bool finish_shutdown_called; /* Is the 'finish_shutdown_locked()' called ? */ + bool shutting_down; /* Is the pollset shutting down ? */ grpc_closure *shutdown_closure; /* Called after after shutdown is complete */ + + /* Number of workers who are *about-to* attach themselves to the pollset + * worker list */ int begin_refs; grpc_pollset *next; @@ -224,7 +249,7 @@ static void fd_shutdown(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_error *why) { static void fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure *on_done, int *release_fd, - const char *reason) { + bool already_closed, const char *reason) { grpc_error *error = GRPC_ERROR_NONE; if (!grpc_lfev_is_shutdown(&fd->read_closure)) { @@ -235,7 +260,7 @@ static void fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, descriptor fd->fd (but we still own the grpc_fd structure). */ if (release_fd != NULL) { *release_fd = fd->fd; - } else { + } else if (!already_closed) { close(fd->fd); } @@ -263,29 +288,23 @@ static bool fd_is_shutdown(grpc_fd *fd) { 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); + grpc_lfev_notify_on(exec_ctx, &fd->read_closure, closure, "read"); } 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); + grpc_lfev_notify_on(exec_ctx, &fd->write_closure, closure, "write"); } 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) */ + grpc_lfev_set_ready(exec_ctx, &fd->read_closure, "read"); /* 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); + grpc_lfev_set_ready(exec_ctx, &fd->write_closure, "write"); } /******************************************************************************* @@ -410,18 +429,28 @@ static grpc_error *pollset_kick_all(grpc_pollset *pollset) { 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"); + switch (worker->kick_state) { + case KICKED: + break; + case UNKICKED: + SET_KICK_STATE(worker, KICKED); + if (worker->initialized_cv) { + gpr_cv_signal(&worker->cv); + } + break; + case DESIGNATED_POLLER: + SET_KICK_STATE(worker, KICKED); + append_error(&error, grpc_wakeup_fd_wakeup(&global_wakeup_fd), + "pollset_kick_all"); + break; } worker = worker->next; } while (worker != pollset->root_worker); } + // TODO: sreek. Check if we need to set 'kicked_without_poller' to true here + // in the else case + return error; } @@ -437,7 +466,9 @@ static void pollset_maybe_finish_shutdown(grpc_exec_ctx *exec_ctx, static void pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, grpc_closure *closure) { GPR_ASSERT(pollset->shutdown_closure == NULL); + GPR_ASSERT(!pollset->shutting_down); pollset->shutdown_closure = closure; + pollset->shutting_down = true; GRPC_LOG_IF_ERROR("pollset_shutdown", pollset_kick_all(pollset)); pollset_maybe_finish_shutdown(exec_ctx, pollset); } @@ -510,10 +541,14 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker, gpr_timespec deadline) { if (worker_hdl != NULL) *worker_hdl = worker; worker->initialized_cv = false; - worker->kick_state = UNKICKED; + SET_KICK_STATE(worker, UNKICKED); worker->schedule_on_end_work = (grpc_closure_list)GRPC_CLOSURE_LIST_INIT; pollset->begin_refs++; + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, "PS:%p BEGIN_STARTS:%p", pollset, worker); + } + if (pollset->seen_inactive) { // pollset has been observed to be inactive, we need to move back to the // active list @@ -529,6 +564,11 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker, retry_lock_neighbourhood: gpr_mu_lock(&neighbourhood->mu); gpr_mu_lock(&pollset->mu); + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, "PS:%p BEGIN_REORG:%p kick_state=%s is_reassigning=%d", + pollset, worker, kick_state_string(worker->kick_state), + is_reassigning); + } if (pollset->seen_inactive) { if (neighbourhood != pollset->neighbourhood) { gpr_mu_unlock(&neighbourhood->mu); @@ -539,8 +579,14 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker, 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; + /* TODO: sreek. Why would this worker state be other than UNKICKED + * here ? (since the worker isn't added to the pollset yet, there is no + * way it can be "found" by other threads to get kicked). */ + + /* If there is no designated poller, make this the designated poller */ + if (worker->kick_state == UNKICKED && + gpr_atm_no_barrier_cas(&g_active_poller, 0, (gpr_atm)worker)) { + SET_KICK_STATE(worker, DESIGNATED_POLLER); } } else { pollset->next = neighbourhood->active_root; @@ -554,24 +600,53 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker, } gpr_mu_unlock(&neighbourhood->mu); } + worker_insert(pollset, worker); pollset->begin_refs--; - if (worker->kick_state == UNKICKED) { + if (worker->kick_state == UNKICKED && !pollset->kicked_without_poller) { 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) { + while (worker->kick_state == UNKICKED && !pollset->shutting_down) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, "PS:%p BEGIN_WAIT:%p kick_state=%s shutdown=%d", + pollset, worker, kick_state_string(worker->kick_state), + pollset->shutting_down); + } + if (gpr_cv_wait(&worker->cv, &pollset->mu, deadline) && worker->kick_state == UNKICKED) { - worker->kick_state = KICKED; + /* If gpr_cv_wait returns true (i.e a timeout), pretend that the worker + received a kick */ + SET_KICK_STATE(worker, KICKED); } } *now = gpr_now(now->clock_type); } - return worker->kick_state == DESIGNATED_POLLER && - pollset->shutdown_closure == NULL; + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, + "PS:%p BEGIN_DONE:%p kick_state=%s shutdown=%d " + "kicked_without_poller: %d", + pollset, worker, kick_state_string(worker->kick_state), + pollset->shutting_down, pollset->kicked_without_poller); + } + + /* We release pollset lock in this function at a couple of places: + * 1. Briefly when assigning pollset to a neighbourhood + * 2. When doing gpr_cv_wait() + * It is possible that 'kicked_without_poller' was set to true during (1) and + * 'shutting_down' is set to true during (1) or (2). If either of them is + * true, this worker cannot do polling */ + /* TODO(sreek): Perhaps there is a better way to handle kicked_without_poller + * case; especially when the worker is the DESIGNATED_POLLER */ + + if (pollset->kicked_without_poller) { + pollset->kicked_without_poller = false; + return false; + } + + return worker->kick_state == DESIGNATED_POLLER && !pollset->shutting_down; } static bool check_neighbourhood_for_available_poller( @@ -591,10 +666,18 @@ static bool check_neighbourhood_for_available_poller( case UNKICKED: if (gpr_atm_no_barrier_cas(&g_active_poller, 0, (gpr_atm)inspect_worker)) { - inspect_worker->kick_state = DESIGNATED_POLLER; + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_DEBUG, " .. choose next poller to be %p", + inspect_worker); + } + SET_KICK_STATE(inspect_worker, DESIGNATED_POLLER); if (inspect_worker->initialized_cv) { gpr_cv_signal(&inspect_worker->cv); } + } else { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_DEBUG, " .. beaten to choose next poller"); + } } // even if we didn't win the cas, there's a worker, we can stop found_worker = true; @@ -607,9 +690,12 @@ static bool check_neighbourhood_for_available_poller( break; } inspect_worker = inspect_worker->next; - } while (inspect_worker != inspect->root_worker); + } while (!found_worker && inspect_worker != inspect->root_worker); } if (!found_worker) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_DEBUG, " .. mark pollset %p inactive", inspect); + } inspect->seen_inactive = true; if (inspect == neighbourhood->active_root) { neighbourhood->active_root = @@ -627,15 +713,22 @@ static bool check_neighbourhood_for_available_poller( static void end_worker(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, grpc_pollset_worker *worker, grpc_pollset_worker **worker_hdl) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_DEBUG, "PS:%p END_WORKER:%p", pollset, worker); + } if (worker_hdl != NULL) *worker_hdl = NULL; - worker->kick_state = KICKED; + /* Make sure we appear kicked */ + SET_KICK_STATE(worker, 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) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_DEBUG, " .. choose next poller to be peer %p", worker); + } GPR_ASSERT(worker->next->initialized_cv); gpr_atm_no_barrier_store(&g_active_poller, (gpr_atm)worker->next); - worker->next->kick_state = DESIGNATED_POLLER; + SET_KICK_STATE(worker->next, DESIGNATED_POLLER); gpr_cv_signal(&worker->next->cv); if (grpc_exec_ctx_has_work(exec_ctx)) { gpr_mu_unlock(&pollset->mu); @@ -644,9 +737,9 @@ static void end_worker(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, } } 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); + gpr_mu_unlock(&pollset->mu); bool found_worker = false; bool scan_state[MAX_NEIGHBOURHOODS]; for (size_t i = 0; !found_worker && i < g_num_neighbourhoods; i++) { @@ -682,6 +775,9 @@ static void end_worker(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, if (worker->initialized_cv) { gpr_cv_destroy(&worker->cv); } + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_DEBUG, " .. remove worker"); + } if (EMPTIED == worker_remove(pollset, worker)) { pollset_maybe_finish_shutdown(exec_ctx, pollset); } @@ -702,16 +798,18 @@ static grpc_error *pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, 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_pollset, (intptr_t)pollset); gpr_tls_set(&g_current_thread_worker, (intptr_t)&worker); - GPR_ASSERT(!pollset->shutdown_closure); + GPR_ASSERT(!pollset->shutting_down); 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); + } else { + gpr_tls_set(&g_current_thread_pollset, (intptr_t)pollset); } end_worker(exec_ctx, pollset, &worker, worker_hdl); gpr_tls_set(&g_current_thread_pollset, 0); @@ -720,46 +818,136 @@ static grpc_error *pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, static grpc_error *pollset_kick(grpc_pollset *pollset, grpc_pollset_worker *specific_worker) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_strvec log; + gpr_strvec_init(&log); + char *tmp; + gpr_asprintf( + &tmp, "PS:%p KICK:%p curps=%p curworker=%p root=%p", pollset, + specific_worker, (void *)gpr_tls_get(&g_current_thread_pollset), + (void *)gpr_tls_get(&g_current_thread_worker), pollset->root_worker); + gpr_strvec_add(&log, tmp); + if (pollset->root_worker != NULL) { + gpr_asprintf(&tmp, " {kick_state=%s next=%p {kick_state=%s}}", + kick_state_string(pollset->root_worker->kick_state), + pollset->root_worker->next, + kick_state_string(pollset->root_worker->next->kick_state)); + gpr_strvec_add(&log, tmp); + } + if (specific_worker != NULL) { + gpr_asprintf(&tmp, " worker_kick_state=%s", + kick_state_string(specific_worker->kick_state)); + gpr_strvec_add(&log, tmp); + } + tmp = gpr_strvec_flatten(&log, NULL); + gpr_strvec_destroy(&log); + gpr_log(GPR_ERROR, "%s", tmp); + gpr_free(tmp); + } 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; + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. kicked_without_poller"); + } 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; + if (root_worker->kick_state == KICKED) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. already kicked %p", root_worker); + } + SET_KICK_STATE(root_worker, KICKED); + return GRPC_ERROR_NONE; + } else if (next_worker->kick_state == KICKED) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. already kicked %p", next_worker); + } + SET_KICK_STATE(next_worker, KICKED); + return GRPC_ERROR_NONE; + } else if (root_worker == + next_worker && // only try and wake up a poller if + // there is no next worker + root_worker == (grpc_pollset_worker *)gpr_atm_no_barrier_load( + &g_active_poller)) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. kicked %p", root_worker); + } + SET_KICK_STATE(root_worker, KICKED); return grpc_wakeup_fd_wakeup(&global_wakeup_fd); } else if (next_worker->kick_state == UNKICKED) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. kicked %p", next_worker); + } GPR_ASSERT(next_worker->initialized_cv); - next_worker->kick_state = KICKED; + SET_KICK_STATE(next_worker, KICKED); gpr_cv_signal(&next_worker->cv); return GRPC_ERROR_NONE; + } else if (next_worker->kick_state == DESIGNATED_POLLER) { + if (root_worker->kick_state != DESIGNATED_POLLER) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log( + GPR_ERROR, + " .. kicked root non-poller %p (initialized_cv=%d) (poller=%p)", + root_worker, root_worker->initialized_cv, next_worker); + } + SET_KICK_STATE(root_worker, KICKED); + if (root_worker->initialized_cv) { + gpr_cv_signal(&root_worker->cv); + } + return GRPC_ERROR_NONE; + } else { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. non-root poller %p (root=%p)", next_worker, + root_worker); + } + SET_KICK_STATE(next_worker, KICKED); + return grpc_wakeup_fd_wakeup(&global_wakeup_fd); + } } else { + GPR_ASSERT(next_worker->kick_state == KICKED); + SET_KICK_STATE(next_worker, KICKED); return GRPC_ERROR_NONE; } } else { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. kicked while waking up"); + } return GRPC_ERROR_NONE; } } else if (specific_worker->kick_state == KICKED) { + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. specific worker already kicked"); + } return GRPC_ERROR_NONE; } else if (gpr_tls_get(&g_current_thread_worker) == (intptr_t)specific_worker) { - specific_worker->kick_state = KICKED; + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. mark %p kicked", specific_worker); + } + SET_KICK_STATE(specific_worker, 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; + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. kick active poller"); + } + SET_KICK_STATE(specific_worker, KICKED); return grpc_wakeup_fd_wakeup(&global_wakeup_fd); } else if (specific_worker->initialized_cv) { - specific_worker->kick_state = KICKED; + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. kick waiting worker"); + } + SET_KICK_STATE(specific_worker, KICKED); gpr_cv_signal(&specific_worker->cv); return GRPC_ERROR_NONE; } else { - specific_worker->kick_state = KICKED; + if (GRPC_TRACER_ON(grpc_polling_trace)) { + gpr_log(GPR_ERROR, " .. kick non-waiting worker"); + } + SET_KICK_STATE(specific_worker, KICKED); return GRPC_ERROR_NONE; } } @@ -805,6 +993,7 @@ static void pollset_set_del_pollset_set(grpc_exec_ctx *exec_ctx, static void shutdown_engine(void) { fd_global_shutdown(); pollset_global_shutdown(); + close(g_epfd); } static const grpc_event_engine_vtable vtable = { @@ -841,9 +1030,6 @@ static const grpc_event_engine_vtable vtable = { /* 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; } @@ -862,6 +1048,8 @@ const grpc_event_engine_vtable *grpc_init_epoll1_linux(bool explicit_request) { return NULL; } + gpr_log(GPR_ERROR, "grpc epoll fd: %d", g_epfd); + return &vtable; } |