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|
/*
*
* Copyright 2016, 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 <grpc/support/port_platform.h>
#ifdef GPR_POSIX_SOCKET
#include "src/core/lib/iomgr/ev_epoll_posix.h"
#include <assert.h>
#include <errno.h>
#include <poll.h>
#include <signal.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/socket.h>
#include <unistd.h>
#include <grpc/support/alloc.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/wakeup_fd_posix.h"
#include "src/core/lib/profiling/timers.h"
#include "src/core/lib/support/block_annotate.h"
struct polling_island;
/*******************************************************************************
* Fd Declarations
*/
struct grpc_fd {
int fd;
/* 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 mu;
bool shutdown;
int closed;
bool released;
grpc_closure *read_closure;
grpc_closure *write_closure;
/* The polling island to which this fd belongs to and the mutex protecting the
the field */
gpr_mu pi_mu;
struct polling_island *polling_island;
struct grpc_fd *freelist_next;
grpc_closure *on_done_closure;
grpc_iomgr_object iomgr_object;
};
/* Reference counting for fds */
#ifdef GRPC_FD_REF_COUNT_DEBUG
static void fd_ref(grpc_fd *fd, const char *reason, const char *file, int line);
static void fd_unref(grpc_fd *fd, const char *reason, const char *file,
int line);
#define GRPC_FD_REF(fd, reason) fd_ref(fd, reason, __FILE__, __LINE__)
#define GRPC_FD_UNREF(fd, reason) fd_unref(fd, reason, __FILE__, __LINE__)
#else
static void fd_ref(grpc_fd *fd);
static void fd_unref(grpc_fd *fd);
#define GRPC_FD_REF(fd, reason) fd_ref(fd)
#define GRPC_FD_UNREF(fd, reason) fd_unref(fd)
#endif
static void fd_global_init(void);
static void fd_global_shutdown(void);
#define CLOSURE_NOT_READY ((grpc_closure *)0)
#define CLOSURE_READY ((grpc_closure *)1)
/*******************************************************************************
* Polling-island Declarations
*/
typedef struct polling_island {
gpr_mu mu;
int ref_cnt;
/* Points to the polling_island this merged into.
* If merged_to is not NULL, all the remaining fields (except mu and ref_cnt)
* are invalid and must be ignored */
struct polling_island *merged_to;
/* The fd of the underlying epoll set */
int epoll_fd;
/* The file descriptors in the epoll set */
size_t fd_cnt;
size_t fd_capacity;
grpc_fd **fds;
/* Polling islands that are no longer needed are kept in a freelist so that
they can be reused. This field points to the next polling island in the
free list */
struct polling_island *next_free;
} polling_island;
/*******************************************************************************
* Pollset Declarations
*/
struct grpc_pollset_worker {
int kicked_specifically;
pthread_t pt_id; /* TODO (sreek) - Add an abstraction here */
struct grpc_pollset_worker *next;
struct grpc_pollset_worker *prev;
};
struct grpc_pollset {
gpr_mu mu;
grpc_pollset_worker root_worker;
bool kicked_without_pollers;
bool shutting_down; /* Is the pollset shutting down ? */
bool finish_shutdown_called; /* Is the 'finish_shutdown_locked()' called ? */
grpc_closure *shutdown_done; /* Called after after shutdown is complete */
/* The polling island to which this pollset belongs to and the mutex
protecting the field */
gpr_mu pi_mu;
struct polling_island *polling_island;
};
/*******************************************************************************
* Pollset-set Declarations
*/
struct grpc_pollset_set {
gpr_mu mu;
size_t pollset_count;
size_t pollset_capacity;
grpc_pollset **pollsets;
size_t pollset_set_count;
size_t pollset_set_capacity;
struct grpc_pollset_set **pollset_sets;
size_t fd_count;
size_t fd_capacity;
grpc_fd **fds;
};
/*******************************************************************************
* Polling-island Definitions
*/
/* Polling island freelist */
static gpr_mu g_pi_freelist_mu;
static polling_island *g_pi_freelist = NULL;
/* The caller is expected to hold pi->mu lock before calling this function */
static void polling_island_add_fds_locked(polling_island *pi, grpc_fd **fds,
size_t fd_count, bool add_fd_refs) {
int err;
size_t i;
struct epoll_event ev;
for (i = 0; i < fd_count; i++) {
ev.events = (uint32_t)(EPOLLIN | EPOLLOUT | EPOLLET);
ev.data.ptr = fds[i];
err = epoll_ctl(pi->epoll_fd, EPOLL_CTL_ADD, fds[i]->fd, &ev);
if (err < 0) {
if (errno != EEXIST) {
/* TODO: sreek - We need a better way to bubble up this error instead of
just logging a message */
gpr_log(GPR_ERROR, "epoll_ctl add for fd: %d failed with error: %s",
fds[i]->fd, strerror(errno));
}
continue;
}
if (pi->fd_cnt == pi->fd_capacity) {
pi->fd_capacity = GPR_MAX(pi->fd_capacity + 8, pi->fd_cnt * 3 / 2);
pi->fds = gpr_realloc(pi->fds, sizeof(grpc_fd *) * pi->fd_capacity);
}
pi->fds[pi->fd_cnt++] = fds[i];
if (add_fd_refs) {
GRPC_FD_REF(fds[i], "polling_island");
}
}
}
/* The caller is expected to hold pi->mu lock before calling this function */
static void polling_island_remove_all_fds_locked(polling_island *pi,
bool remove_fd_refs) {
int err;
size_t i;
for (i = 0; i < pi->fd_cnt; i++) {
if (remove_fd_refs) {
GRPC_FD_UNREF(pi->fds[i], "polling_island");
}
err = epoll_ctl(pi->epoll_fd, EPOLL_CTL_DEL, pi->fds[i]->fd, NULL);
if (err < 0 && errno != ENOENT) {
gpr_log(GPR_ERROR,
"epoll_ctl delete for fds[i]: %d failed with error: %s", i,
pi->fds[i]->fd, strerror(errno));
/* TODO: sreek - We need a better way to bubble up this error instead of
* just logging a message */
continue;
}
}
pi->fd_cnt = 0;
}
/* The caller is expected to hold pi->mu lock before calling this function */
static void polling_island_remove_fd_locked(polling_island *pi, grpc_fd *fd,
bool close_fd, bool remove_fd_ref) {
int err;
size_t i;
/* Calling close() on the fd will automatically remove it from the epoll set.
If not calling close(), the fd must be explicitly removed from the epoll
set */
if (close_fd) {
close(fd->fd);
} else {
err = epoll_ctl(pi->epoll_fd, EPOLL_CTL_DEL, fd->fd, NULL);
if (err < 0 && errno != ENOENT) {
gpr_log(GPR_ERROR, "epoll_ctl delete for fd: %d failed with error; %s",
fd->fd, strerror(errno));
}
}
for (i = 0; i < pi->fd_cnt; i++) {
if (pi->fds[i] == fd) {
pi->fds[i] = pi->fds[--pi->fd_cnt];
if (remove_fd_ref) {
GRPC_FD_UNREF(fd, "polling_island");
}
break;
}
}
}
static polling_island *polling_island_create(grpc_fd *initial_fd,
int initial_ref_cnt) {
polling_island *pi = NULL;
struct epoll_event ev;
int err;
/* Try to get one from the polling island freelist */
gpr_mu_lock(&g_pi_freelist_mu);
if (g_pi_freelist != NULL) {
pi = g_pi_freelist;
g_pi_freelist = g_pi_freelist->next_free;
pi->next_free = NULL;
}
gpr_mu_unlock(&g_pi_freelist_mu);
/* Create new polling island if we could not get one from the free list */
if (pi == NULL) {
pi = gpr_malloc(sizeof(*pi));
gpr_mu_init(&pi->mu);
pi->fd_cnt = 0;
pi->fd_capacity = 0;
pi->fds = NULL;
}
pi->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
if (pi->epoll_fd < 0) {
gpr_log(GPR_ERROR, "epoll_create1() failed with error: %s",
strerror(errno));
}
GPR_ASSERT(pi->epoll_fd >= 0);
ev.events = (uint32_t)(EPOLLIN | EPOLLET);
ev.data.ptr = NULL;
err = epoll_ctl(pi->epoll_fd, EPOLL_CTL_ADD,
GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd), &ev);
if (err < 0) {
gpr_log(GPR_ERROR,
"Failed to add grpc_global_wake_up_fd (%d) to the epoll set "
"(epoll_fd: %d) with error: %s",
GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd), pi->epoll_fd,
strerror(errno));
}
pi->ref_cnt = initial_ref_cnt;
pi->merged_to = NULL;
pi->next_free = NULL;
if (initial_fd != NULL) {
/* It is not really needed to get the pi->mu lock here. If this is a newly
created polling island (or one that we got from the freelist), no one
else would be holding a lock to it anyway */
gpr_mu_lock(&pi->mu);
polling_island_add_fds_locked(pi, &initial_fd, 1, true);
gpr_mu_unlock(&pi->mu);
}
return pi;
}
static void polling_island_delete(polling_island *pi) {
GPR_ASSERT(pi->ref_cnt == 0);
GPR_ASSERT(pi->fd_cnt == 0);
close(pi->epoll_fd);
pi->epoll_fd = -1;
pi->merged_to = NULL;
gpr_mu_lock(&g_pi_freelist_mu);
pi->next_free = g_pi_freelist;
g_pi_freelist = pi;
gpr_mu_unlock(&g_pi_freelist_mu);
}
void polling_island_unref_and_unlock(polling_island *pi, int unref_by) {
pi->ref_cnt -= unref_by;
int ref_cnt = pi->ref_cnt;
GPR_ASSERT(ref_cnt >= 0);
gpr_mu_unlock(&pi->mu);
if (ref_cnt == 0) {
polling_island_delete(pi);
}
}
polling_island *polling_island_update_and_lock(polling_island *pi, int unref_by,
int add_ref_by) {
polling_island *next = NULL;
gpr_mu_lock(&pi->mu);
while (pi->merged_to != NULL) {
next = pi->merged_to;
polling_island_unref_and_unlock(pi, unref_by);
pi = next;
gpr_mu_lock(&pi->mu);
}
pi->ref_cnt += add_ref_by;
return pi;
}
void polling_island_pair_update_and_lock(polling_island **p,
polling_island **q) {
polling_island *pi_1 = *p;
polling_island *pi_2 = *q;
polling_island *temp = NULL;
bool pi_1_locked = false;
bool pi_2_locked = false;
int num_swaps = 0;
/* Loop until either pi_1 == pi_2 or until we acquired locks on both pi_1
and pi_2 */
while (pi_1 != pi_2 && !(pi_1_locked && pi_2_locked)) {
/* The following assertions are true at this point:
- pi_1 != pi_2 (else, the while loop would have exited)
- pi_1 MAY be locked
- pi_2 is NOT locked */
/* To maintain lock order consistency, always lock polling_island node with
lower address first.
First, make sure pi_1 < pi_2 before proceeding any further. If it turns
out that pi_1 > pi_2, unlock pi_1 if locked (because pi_2 is not locked
at this point and having pi_1 locked would violate the lock order) and
swap pi_1 and pi_2 so that pi_1 becomes less than pi_2 */
if (pi_1 > pi_2) {
if (pi_1_locked) {
gpr_mu_unlock(&pi_1->mu);
pi_1_locked = false;
}
GPR_SWAP(polling_island *, pi_1, pi_2);
num_swaps++;
}
/* The following assertions are true at this point:
- pi_1 != pi_2
- pi_1 < pi_2 (address of pi_1 is less than that of pi_2)
- pi_1 MAYBE locked
- pi_2 is NOT locked */
/* Lock pi_1 (if pi_1 is pointing to the terminal node in the list) */
if (!pi_1_locked) {
gpr_mu_lock(&pi_1->mu);
pi_1_locked = true;
/* If pi_1 is not terminal node (i.e pi_1->merged_to != NULL), we are not
done locking this polling_island yet. Release the lock on this node and
advance pi_1 to the next node in the list; and go to the beginning of
the loop (we can't proceed to locking pi_2 unless we locked pi_1 first)
*/
if (pi_1->merged_to != NULL) {
temp = pi_1->merged_to;
polling_island_unref_and_unlock(pi_1, 1);
pi_1 = temp;
pi_1_locked = false;
continue;
}
}
/* The following assertions are true at this point:
- pi_1 is locked
- pi_2 is unlocked
- pi_1 != pi_2 */
gpr_mu_lock(&pi_2->mu);
pi_2_locked = true;
/* If pi_2 is not terminal node, we are not done locking this polling_island
yet. Release the lock and update pi_2 to the next node in the list */
if (pi_2->merged_to != NULL) {
temp = pi_2->merged_to;
polling_island_unref_and_unlock(pi_2, 1);
pi_2 = temp;
pi_2_locked = false;
}
}
/* At this point, either pi_1 == pi_2 AND/OR we got both locks */
if (pi_1 == pi_2) {
/* We may or may not have gotten the lock. If we didn't, walk the rest of
the polling_island list and get the lock */
GPR_ASSERT(pi_1_locked || (!pi_1_locked && !pi_2_locked));
if (!pi_1_locked) {
pi_1 = pi_2 = polling_island_update_and_lock(pi_1, 2, 0);
}
} else {
GPR_ASSERT(pi_1_locked && pi_2_locked);
/* If we swapped pi_1 and pi_2 odd number of times, do one more swap so that
pi_1 and pi_2 point to the same polling_island lists they started off
with at the beginning of this function (i.e *p and *q respectively) */
if (num_swaps % 2 > 0) {
GPR_SWAP(polling_island *, pi_1, pi_2);
}
}
*p = pi_1;
*q = pi_2;
}
polling_island *polling_island_merge(polling_island *p, polling_island *q) {
/* Get locks on both the polling islands */
polling_island_pair_update_and_lock(&p, &q);
/* TODO: sreek: Think about this scenario some more. Is it possible ?. what
* does it mean, when would this happen */
if (p == q) {
/* Nothing needs to be done here */
gpr_mu_unlock(&p->mu);
return p;
}
/* Make sure that p points to the polling island with fewer fds than q */
if (p->fd_cnt > q->fd_cnt) {
GPR_SWAP(polling_island *, p, q);
}
/* "Merge" p with q i.e move all the fds from p (the polling_island with fewer
fds) to q.
Note: Not altering the ref counts on the affected fds here because they
would effectively remain unchanged */
polling_island_add_fds_locked(q, p->fds, p->fd_cnt, false);
polling_island_remove_all_fds_locked(p, false);
/* The merged polling island inherits all the ref counts of the island merging
with it */
q->ref_cnt += p->ref_cnt;
gpr_mu_unlock(&p->mu);
gpr_mu_unlock(&q->mu);
return q;
}
static void polling_island_global_init() {
gpr_mu_init(&g_pi_freelist_mu);
g_pi_freelist = NULL;
}
/*******************************************************************************
* 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. */
/* TODO: sreek: Right now, this wakes up all pollers */
grpc_wakeup_fd grpc_global_wakeup_fd;
static grpc_fd *fd_freelist = NULL;
static gpr_mu fd_freelist_mu;
#ifdef GRPC_FD_REF_COUNT_DEBUG
#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) {
gpr_log(GPR_DEBUG, "FD %d %p ref %d %d -> %d [%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);
}
#ifdef GRPC_FD_REF_COUNT_DEBUG
static void unref_by(grpc_fd *fd, int n, const char *reason, const char *file,
int line) {
gpr_atm old;
gpr_log(GPR_DEBUG, "FD %d %p unref %d %d -> %d [%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) {
gpr_atm old;
#endif
old = gpr_atm_full_fetch_add(&fd->refst, -n);
if (old == n) {
/* Add the fd to the freelist */
gpr_mu_lock(&fd_freelist_mu);
fd->freelist_next = fd_freelist;
fd_freelist = fd;
grpc_iomgr_unregister_object(&fd->iomgr_object);
gpr_mu_unlock(&fd_freelist_mu);
} else {
GPR_ASSERT(old > n);
}
}
/* Increment refcount by two to avoid changing the orphan bit */
#ifdef GRPC_FD_REF_COUNT_DEBUG
static void fd_ref(grpc_fd *fd, const char *reason, const char *file,
int line) {
ref_by(fd, 2, reason, file, line);
}
static void fd_unref(grpc_fd *fd, const char *reason, const char *file,
int line) {
unref_by(fd, 2, reason, file, line);
}
#else
static void fd_ref(grpc_fd *fd) { ref_by(fd, 2); }
static void fd_unref(grpc_fd *fd) { unref_by(fd, 2); }
#endif
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_mu_destroy(&fd->mu);
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));
gpr_mu_init(&new_fd->mu);
gpr_mu_init(&new_fd->pi_mu);
}
/* Note: It is not really needed to get the new_fd->mu lock here. If this is a
newly created fd (or an fd we got from the freelist), no one else would be
holding a lock to it anyway. */
gpr_mu_lock(&new_fd->mu);
gpr_atm_rel_store(&new_fd->refst, 1);
new_fd->shutdown = false;
new_fd->read_closure = CLOSURE_NOT_READY;
new_fd->write_closure = CLOSURE_NOT_READY;
new_fd->fd = fd;
new_fd->polling_island = NULL;
new_fd->freelist_next = NULL;
new_fd->on_done_closure = NULL;
new_fd->closed = 0;
new_fd->released = false;
gpr_mu_unlock(&new_fd->mu);
char *fd_name;
gpr_asprintf(&fd_name, "%s fd=%d", name, fd);
grpc_iomgr_register_object(&new_fd->iomgr_object, fd_name);
gpr_free(fd_name);
#ifdef GRPC_FD_REF_COUNT_DEBUG
gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, r, fd_name);
#endif
return new_fd;
}
static bool fd_is_orphaned(grpc_fd *fd) {
return (gpr_atm_acq_load(&fd->refst) & 1) == 0;
}
static int fd_wrapped_fd(grpc_fd *fd) {
int ret_fd = -1;
gpr_mu_lock(&fd->mu);
if (!fd->released && !fd->closed) {
ret_fd = fd->fd;
}
gpr_mu_unlock(&fd->mu);
return ret_fd;
}
static void fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
grpc_closure *on_done, int *release_fd,
const char *reason) {
/* TODO(sreek) In ev_poll_posix.c,the lock is acquired a little later. Why? */
gpr_mu_lock(&fd->mu);
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). */
fd->released = release_fd != NULL;
if (!fd->released) {
shutdown(fd->fd, SHUT_RDWR);
} else {
*release_fd = fd->fd;
}
REF_BY(fd, 1, reason); /* Remove active status, but keep referenced */
fd->closed = 1;
/* Remove the fd from the polling island:
- Update the fd->polling_island to point to the latest polling island
- Remove the fd from the polling island. Also, call close() on the file
descriptor fd->fd ONLY if we haven't relinquised control (i.e
fd->released is 'false')
- Decrement the ref count on the polling island and det fd->polling_island
to NULL */
gpr_mu_lock(&fd->pi_mu);
if (fd->polling_island != NULL) {
fd->polling_island =
polling_island_update_and_lock(fd->polling_island, 1, 0);
polling_island_remove_fd_locked(fd->polling_island, fd, !fd->released,
true);
polling_island_unref_and_unlock(fd->polling_island, 1);
fd->polling_island = NULL;
}
gpr_mu_unlock(&fd->pi_mu);
grpc_exec_ctx_enqueue(exec_ctx, fd->on_done_closure, true, NULL);
gpr_mu_unlock(&fd->mu);
UNREF_BY(fd, 2, reason); /* Drop the reference */
}
static void notify_on_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
grpc_closure **st, grpc_closure *closure) {
if (*st == CLOSURE_NOT_READY) {
/* not ready ==> switch to a waiting state by setting the closure */
*st = closure;
} else if (*st == CLOSURE_READY) {
/* already ready ==> queue the closure to run immediately */
*st = CLOSURE_NOT_READY;
grpc_exec_ctx_enqueue(exec_ctx, closure, !fd->shutdown, NULL);
} else {
/* upcallptr was set to a different closure. This is an error! */
gpr_log(GPR_ERROR,
"User called a notify_on function with a previous callback still "
"pending");
abort();
}
}
/* returns 1 if state becomes not ready */
static int set_ready_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
grpc_closure **st) {
if (*st == CLOSURE_READY) {
/* duplicate ready ==> ignore */
return 0;
} else if (*st == CLOSURE_NOT_READY) {
/* not ready, and not waiting ==> flag ready */
*st = CLOSURE_READY;
return 0;
} else {
/* waiting ==> queue closure */
grpc_exec_ctx_enqueue(exec_ctx, *st, !fd->shutdown, NULL);
*st = CLOSURE_NOT_READY;
return 1;
}
}
static void fd_shutdown(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
gpr_mu_lock(&fd->mu);
GPR_ASSERT(!fd->shutdown);
fd->shutdown = true;
/* Flush any pending read and write closures. Since fd->shutdown is 'true' at
this point, the closures would be called with 'success = false' */
set_ready_locked(exec_ctx, fd, &fd->read_closure);
set_ready_locked(exec_ctx, fd, &fd->write_closure);
gpr_mu_unlock(&fd->mu);
}
static void fd_notify_on_read(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
grpc_closure *closure) {
gpr_mu_lock(&fd->mu);
notify_on_locked(exec_ctx, fd, &fd->read_closure, closure);
gpr_mu_unlock(&fd->mu);
}
static void fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
grpc_closure *closure) {
gpr_mu_lock(&fd->mu);
notify_on_locked(exec_ctx, fd, &fd->write_closure, closure);
gpr_mu_unlock(&fd->mu);
}
/*******************************************************************************
* Pollset Definitions
*/
static void sig_handler(int sig_num) {
/* TODO: sreek - Remove this expensive log line */
gpr_log(GPR_INFO, "Received signal %d", sig_num);
}
/* Global state management */
static void pollset_global_init(void) {
grpc_wakeup_fd_init(&grpc_global_wakeup_fd);
signal(SIGUSR1, sig_handler);
}
static void pollset_global_shutdown(void) {
grpc_wakeup_fd_destroy(&grpc_global_wakeup_fd);
}
/* Return 1 if the pollset has active threads in pollset_work (pollset must
* be locked) */
static int pollset_has_workers(grpc_pollset *p) {
return p->root_worker.next != &p->root_worker;
}
static void remove_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
worker->prev->next = worker->next;
worker->next->prev = worker->prev;
}
static grpc_pollset_worker *pop_front_worker(grpc_pollset *p) {
if (pollset_has_workers(p)) {
grpc_pollset_worker *w = p->root_worker.next;
remove_worker(p, w);
return w;
} else {
return NULL;
}
}
static void push_back_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
worker->next = &p->root_worker;
worker->prev = worker->next->prev;
worker->prev->next = worker->next->prev = worker;
}
static void push_front_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
worker->prev = &p->root_worker;
worker->next = worker->prev->next;
worker->prev->next = worker->next->prev = worker;
}
/* p->mu must be held before calling this function */
static void pollset_kick(grpc_pollset *p,
grpc_pollset_worker *specific_worker) {
GPR_TIMER_BEGIN("pollset_kick", 0);
grpc_pollset_worker *worker = specific_worker;
if (worker != NULL) {
if (worker == GRPC_POLLSET_KICK_BROADCAST) {
GPR_TIMER_BEGIN("pollset_kick.broadcast", 0);
if (pollset_has_workers(p)) {
for (worker = p->root_worker.next; worker != &p->root_worker;
worker = worker->next) {
pthread_kill(worker->pt_id, SIGUSR1);
}
} else {
p->kicked_without_pollers = true;
}
GPR_TIMER_END("pollset_kick.broadcast", 0);
} else {
GPR_TIMER_MARK("kicked_specifically", 0);
worker->kicked_specifically = true;
pthread_kill(worker->pt_id, SIGUSR1);
}
} else {
GPR_TIMER_MARK("kick_anonymous", 0);
worker = pop_front_worker(p);
if (worker != NULL) {
GPR_TIMER_MARK("finally_kick", 0);
push_back_worker(p, worker);
pthread_kill(worker->pt_id, SIGUSR1);
} else {
GPR_TIMER_MARK("kicked_no_pollers", 0);
p->kicked_without_pollers = true;
}
}
GPR_TIMER_END("pollset_kick", 0);
}
static void kick_poller(void) { grpc_wakeup_fd_wakeup(&grpc_global_wakeup_fd); }
static void pollset_init(grpc_pollset *pollset, gpr_mu **mu) {
gpr_mu_init(&pollset->mu);
*mu = &pollset->mu;
pollset->root_worker.next = pollset->root_worker.prev = &pollset->root_worker;
pollset->kicked_without_pollers = false;
pollset->shutting_down = false;
pollset->finish_shutdown_called = false;
pollset->shutdown_done = NULL;
gpr_mu_init(&pollset->pi_mu);
pollset->polling_island = NULL;
}
/* Convert a timespec to milliseconds:
- Very small or negative poll times are clamped to zero to do a non-blocking
poll (which becomes spin polling)
- Other small values are rounded up to one millisecond
- Longer than a millisecond polls are rounded up to the next nearest
millisecond to avoid spinning
- Infinite timeouts are converted to -1 */
static int poll_deadline_to_millis_timeout(gpr_timespec deadline,
gpr_timespec now) {
gpr_timespec timeout;
static const int64_t max_spin_polling_us = 10;
if (gpr_time_cmp(deadline, gpr_inf_future(deadline.clock_type)) == 0) {
return -1;
}
if (gpr_time_cmp(deadline, gpr_time_add(now, gpr_time_from_micros(
max_spin_polling_us,
GPR_TIMESPAN))) <= 0) {
return 0;
}
timeout = gpr_time_sub(deadline, now);
return gpr_time_to_millis(gpr_time_add(
timeout, gpr_time_from_nanos(GPR_NS_PER_MS - 1, GPR_TIMESPAN)));
}
static void set_ready(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure **st) {
/* only one set_ready can be active at once (but there may be a racing
notify_on) */
gpr_mu_lock(&fd->mu);
set_ready_locked(exec_ctx, fd, st);
gpr_mu_unlock(&fd->mu);
}
static void fd_become_readable(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
set_ready(exec_ctx, fd, &fd->read_closure);
}
static void fd_become_writable(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
set_ready(exec_ctx, fd, &fd->write_closure);
}
#define GRPC_EPOLL_MAX_EVENTS 1000
static void pollset_work_and_unlock(grpc_exec_ctx *exec_ctx,
grpc_pollset *pollset, int timeout_ms,
sigset_t *sig_mask) {
struct epoll_event ep_ev[GRPC_EPOLL_MAX_EVENTS];
int epoll_fd = -1;
int ep_rv;
GPR_TIMER_BEGIN("pollset_work_and_unlock", 0);
/* We need to get the epoll_fd to wait on. The epoll_fd is in inside the
polling island pointed by pollset->polling_island.
Acquire the following locks:
- pollset->mu (which we already have)
- pollset->pi_mu
- pollset->polling_island->mu */
gpr_mu_lock(&pollset->pi_mu);
if (pollset->polling_island != NULL) {
pollset->polling_island =
polling_island_update_and_lock(pollset->polling_island, 1, 0);
epoll_fd = pollset->polling_island->epoll_fd;
gpr_mu_unlock(&pollset->polling_island->mu);
}
gpr_mu_unlock(&pollset->pi_mu);
gpr_mu_unlock(&pollset->mu);
/* If epoll_fd == -1, this is a blank pollset and does not have any fds yet */
if (epoll_fd != -1) {
do {
ep_rv = epoll_pwait(epoll_fd, ep_ev, GRPC_EPOLL_MAX_EVENTS, timeout_ms,
sig_mask);
if (ep_rv < 0) {
if (errno != EINTR) {
/* TODO (sreek) - Check for bad file descriptor error */
gpr_log(GPR_ERROR, "epoll_pwait() failed: %s", strerror(errno));
}
} else {
int i;
for (i = 0; i < ep_rv; ++i) {
grpc_fd *fd = ep_ev[i].data.ptr;
int cancel = ep_ev[i].events & (EPOLLERR | EPOLLHUP);
int read_ev = ep_ev[i].events & (EPOLLIN | EPOLLPRI);
int write_ev = ep_ev[i].events & EPOLLOUT;
if (fd == NULL) {
grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd);
} else {
if (read_ev || cancel) {
fd_become_readable(exec_ctx, fd);
}
if (write_ev || cancel) {
fd_become_writable(exec_ctx, fd);
}
}
}
}
} while (ep_rv == GRPC_EPOLL_MAX_EVENTS);
}
GPR_TIMER_END("pollset_work_and_unlock", 0);
}
/* Release the reference to pollset->polling_island and set it to NULL.
pollset->mu must be held */
static void pollset_release_polling_island_locked(grpc_pollset *pollset) {
gpr_mu_lock(&pollset->pi_mu);
if (pollset->polling_island) {
pollset->polling_island =
polling_island_update_and_lock(pollset->polling_island, 1, 0);
polling_island_unref_and_unlock(pollset->polling_island, 1);
pollset->polling_island = NULL;
}
gpr_mu_unlock(&pollset->pi_mu);
}
static void finish_shutdown_locked(grpc_exec_ctx *exec_ctx,
grpc_pollset *pollset) {
/* The pollset cannot have any workers if we are at this stage */
GPR_ASSERT(!pollset_has_workers(pollset));
pollset->finish_shutdown_called = true;
pollset_release_polling_island_locked(pollset);
grpc_exec_ctx_enqueue(exec_ctx, pollset->shutdown_done, true, NULL);
}
/* pollset->mu lock must be held by the caller before calling this */
static void pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
grpc_closure *closure) {
GPR_TIMER_BEGIN("pollset_shutdown", 0);
GPR_ASSERT(!pollset->shutting_down);
pollset->shutting_down = true;
pollset->shutdown_done = closure;
pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
/* If the pollset has any workers, we cannot call finish_shutdown_locked()
because it would release the underlying polling island. In such a case, we
let the last worker call finish_shutdown_locked() from pollset_work() */
if (!pollset_has_workers(pollset)) {
GPR_ASSERT(!pollset->finish_shutdown_called);
GPR_TIMER_MARK("pollset_shutdown.finish_shutdown_locked", 0);
finish_shutdown_locked(exec_ctx, pollset);
}
GPR_TIMER_END("pollset_shutdown", 0);
}
/* TODO(sreek) Is pollset_shutdown() guranteed to be called before this? */
static void pollset_destroy(grpc_pollset *pollset) {
GPR_ASSERT(!pollset_has_workers(pollset));
gpr_mu_destroy(&pollset->pi_mu);
gpr_mu_destroy(&pollset->mu);
}
static void pollset_reset(grpc_pollset *pollset) {
GPR_ASSERT(pollset->shutting_down);
GPR_ASSERT(!pollset_has_workers(pollset));
pollset->shutting_down = false;
pollset->finish_shutdown_called = false;
pollset->kicked_without_pollers = false;
/* TODO(sreek) - Should pollset->shutdown closure be set to NULL here? */
pollset_release_polling_island_locked(pollset);
}
/* pollset->mu lock must be held by the caller before calling this.
The function pollset_work() may temporarily release the lock (pollset->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 void pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
grpc_pollset_worker **worker_hdl, gpr_timespec now,
gpr_timespec deadline) {
GPR_TIMER_BEGIN("pollset_work", 0);
int timeout_ms = poll_deadline_to_millis_timeout(deadline, now);
sigset_t new_mask;
sigset_t orig_mask;
grpc_pollset_worker worker;
worker.next = worker.prev = NULL;
worker.kicked_specifically = 0;
worker.pt_id = pthread_self();
*worker_hdl = &worker;
if (pollset->kicked_without_pollers) {
/* If the pollset was kicked without pollers, pretend that the current
worker got the kick and skip polling. A kick indicates that there is some
work that needs attention like an event on the completion queue or an
alarm */
GPR_TIMER_MARK("pollset_work.kicked_without_pollers", 0);
pollset->kicked_without_pollers = 0;
} else if (!pollset->shutting_down) {
sigemptyset(&new_mask);
sigaddset(&new_mask, SIGUSR1);
pthread_sigmask(SIG_BLOCK, &new_mask, &orig_mask);
sigdelset(&orig_mask, SIGUSR1);
push_front_worker(pollset, &worker);
pollset_work_and_unlock(exec_ctx, pollset, timeout_ms, &orig_mask);
grpc_exec_ctx_flush(exec_ctx);
gpr_mu_lock(&pollset->mu);
remove_worker(pollset, &worker);
}
/* If we are the last worker on the pollset (i.e pollset_has_workers() is
false at this point) and the pollset is shutting down, we may have to
finish the shutdown process by calling finish_shutdown_locked().
See pollset_shutdown() for more details.
Note: Continuing to access pollset here is safe; it is the caller's
responsibility to not destroy a pollset when it has outstanding calls to
pollset_work() */
if (pollset->shutting_down && !pollset_has_workers(pollset) &&
!pollset->finish_shutdown_called) {
GPR_TIMER_MARK("pollset_work.finish_shutdown_locked", 0);
finish_shutdown_locked(exec_ctx, pollset);
gpr_mu_unlock(&pollset->mu);
grpc_exec_ctx_flush(exec_ctx);
gpr_mu_lock(&pollset->mu);
}
*worker_hdl = NULL;
GPR_TIMER_END("pollset_work", 0);
}
static void pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
grpc_fd *fd) {
/* TODO sreek - Check if we need to get a pollset->mu lock here */
gpr_mu_lock(&pollset->pi_mu);
gpr_mu_lock(&fd->pi_mu);
polling_island *pi_new = NULL;
/* 1) If fd->polling_island and pollset->polling_island are both non-NULL and
* equal, do nothing.
* 2) If fd->polling_island and pollset->polling_island are both NULL, create
* a new polling island (with a refcount of 2) and make the polling_island
* fields in both fd and pollset to point to the new island
* 3) If one of fd->polling_island or pollset->polling_island is NULL, update
* the NULL polling_island field to point to the non-NULL polling_island
* field (ensure that the refcount on the polling island is incremented by
* 1 to account for the newly added reference)
* 4) Finally, if fd->polling_island and pollset->polling_island are non-NULL
* and different, merge both the polling islands and update the
* polling_island fields in both fd and pollset to point to the merged
* polling island.
*/
if (fd->polling_island == pollset->polling_island) {
pi_new = fd->polling_island;
if (pi_new == NULL) {
pi_new = polling_island_create(fd, 2);
}
} else if (fd->polling_island == NULL) {
pi_new = polling_island_update_and_lock(pollset->polling_island, 1, 1);
gpr_mu_unlock(&pi_new->mu);
} else if (pollset->polling_island == NULL) {
pi_new = polling_island_update_and_lock(fd->polling_island, 1, 1);
gpr_mu_unlock(&pi_new->mu);
} else {
pi_new = polling_island_merge(fd->polling_island, pollset->polling_island);
}
fd->polling_island = pollset->polling_island = pi_new;
gpr_mu_unlock(&fd->pi_mu);
gpr_mu_unlock(&pollset->pi_mu);
}
/*******************************************************************************
* Pollset-set Definitions
*/
static grpc_pollset_set *pollset_set_create(void) {
grpc_pollset_set *pollset_set = gpr_malloc(sizeof(*pollset_set));
memset(pollset_set, 0, sizeof(*pollset_set));
gpr_mu_init(&pollset_set->mu);
return pollset_set;
}
static void pollset_set_destroy(grpc_pollset_set *pollset_set) {
size_t i;
gpr_mu_destroy(&pollset_set->mu);
for (i = 0; i < pollset_set->fd_count; i++) {
GRPC_FD_UNREF(pollset_set->fds[i], "pollset_set");
}
gpr_free(pollset_set->pollsets);
gpr_free(pollset_set->pollset_sets);
gpr_free(pollset_set->fds);
gpr_free(pollset_set);
}
static void pollset_set_add_fd(grpc_exec_ctx *exec_ctx,
grpc_pollset_set *pollset_set, grpc_fd *fd) {
size_t i;
gpr_mu_lock(&pollset_set->mu);
if (pollset_set->fd_count == pollset_set->fd_capacity) {
pollset_set->fd_capacity = GPR_MAX(8, 2 * pollset_set->fd_capacity);
pollset_set->fds = gpr_realloc(
pollset_set->fds, pollset_set->fd_capacity * sizeof(*pollset_set->fds));
}
GRPC_FD_REF(fd, "pollset_set");
pollset_set->fds[pollset_set->fd_count++] = fd;
for (i = 0; i < pollset_set->pollset_count; i++) {
pollset_add_fd(exec_ctx, pollset_set->pollsets[i], fd);
}
for (i = 0; i < pollset_set->pollset_set_count; i++) {
pollset_set_add_fd(exec_ctx, pollset_set->pollset_sets[i], fd);
}
gpr_mu_unlock(&pollset_set->mu);
}
static void pollset_set_del_fd(grpc_exec_ctx *exec_ctx,
grpc_pollset_set *pollset_set, grpc_fd *fd) {
size_t i;
gpr_mu_lock(&pollset_set->mu);
for (i = 0; i < pollset_set->fd_count; i++) {
if (pollset_set->fds[i] == fd) {
pollset_set->fd_count--;
GPR_SWAP(grpc_fd *, pollset_set->fds[i],
pollset_set->fds[pollset_set->fd_count]);
GRPC_FD_UNREF(fd, "pollset_set");
break;
}
}
for (i = 0; i < pollset_set->pollset_set_count; i++) {
pollset_set_del_fd(exec_ctx, pollset_set->pollset_sets[i], fd);
}
gpr_mu_unlock(&pollset_set->mu);
}
static void pollset_set_add_pollset(grpc_exec_ctx *exec_ctx,
grpc_pollset_set *pollset_set,
grpc_pollset *pollset) {
size_t i, j;
gpr_mu_lock(&pollset_set->mu);
if (pollset_set->pollset_count == pollset_set->pollset_capacity) {
pollset_set->pollset_capacity =
GPR_MAX(8, 2 * pollset_set->pollset_capacity);
pollset_set->pollsets =
gpr_realloc(pollset_set->pollsets, pollset_set->pollset_capacity *
sizeof(*pollset_set->pollsets));
}
pollset_set->pollsets[pollset_set->pollset_count++] = pollset;
for (i = 0, j = 0; i < pollset_set->fd_count; i++) {
if (fd_is_orphaned(pollset_set->fds[i])) {
GRPC_FD_UNREF(pollset_set->fds[i], "pollset_set");
} else {
pollset_add_fd(exec_ctx, pollset, pollset_set->fds[i]);
pollset_set->fds[j++] = pollset_set->fds[i];
}
}
pollset_set->fd_count = j;
gpr_mu_unlock(&pollset_set->mu);
}
static void pollset_set_del_pollset(grpc_exec_ctx *exec_ctx,
grpc_pollset_set *pollset_set,
grpc_pollset *pollset) {
size_t i;
gpr_mu_lock(&pollset_set->mu);
for (i = 0; i < pollset_set->pollset_count; i++) {
if (pollset_set->pollsets[i] == pollset) {
pollset_set->pollset_count--;
GPR_SWAP(grpc_pollset *, pollset_set->pollsets[i],
pollset_set->pollsets[pollset_set->pollset_count]);
break;
}
}
gpr_mu_unlock(&pollset_set->mu);
}
static void pollset_set_add_pollset_set(grpc_exec_ctx *exec_ctx,
grpc_pollset_set *bag,
grpc_pollset_set *item) {
size_t i, j;
gpr_mu_lock(&bag->mu);
if (bag->pollset_set_count == bag->pollset_set_capacity) {
bag->pollset_set_capacity = GPR_MAX(8, 2 * bag->pollset_set_capacity);
bag->pollset_sets =
gpr_realloc(bag->pollset_sets,
bag->pollset_set_capacity * sizeof(*bag->pollset_sets));
}
bag->pollset_sets[bag->pollset_set_count++] = item;
for (i = 0, j = 0; i < bag->fd_count; i++) {
if (fd_is_orphaned(bag->fds[i])) {
GRPC_FD_UNREF(bag->fds[i], "pollset_set");
} else {
pollset_set_add_fd(exec_ctx, item, bag->fds[i]);
bag->fds[j++] = bag->fds[i];
}
}
bag->fd_count = j;
gpr_mu_unlock(&bag->mu);
}
static void pollset_set_del_pollset_set(grpc_exec_ctx *exec_ctx,
grpc_pollset_set *bag,
grpc_pollset_set *item) {
size_t i;
gpr_mu_lock(&bag->mu);
for (i = 0; i < bag->pollset_set_count; i++) {
if (bag->pollset_sets[i] == item) {
bag->pollset_set_count--;
GPR_SWAP(grpc_pollset_set *, bag->pollset_sets[i],
bag->pollset_sets[bag->pollset_set_count]);
break;
}
}
gpr_mu_unlock(&bag->mu);
}
/*******************************************************************************
* 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_notify_on_read = fd_notify_on_read,
.fd_notify_on_write = fd_notify_on_write,
.pollset_init = pollset_init,
.pollset_shutdown = pollset_shutdown,
.pollset_reset = pollset_reset,
.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,
.kick_poller = kick_poller,
.shutdown_engine = shutdown_engine,
};
const grpc_event_engine_vtable *grpc_init_epoll_linux(void) {
fd_global_init();
pollset_global_init();
polling_island_global_init();
return &vtable;
}
#endif
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