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-rw-r--r--.gitignore1
-rw-r--r--Makefile.am9
-rw-r--r--src/shared/barrier.c440
-rw-r--r--src/shared/barrier.h92
-rw-r--r--src/test/test-barrier.c460
5 files changed, 1002 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore
index bf53064105..48606313cc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -124,6 +124,7 @@
/tags
/test-architecture
/test-async
+/test-barrier
/test-boot-timestamp
/test-bus-chat
/test-bus-cleanup
diff --git a/Makefile.am b/Makefile.am
index 7025137683..f0d80ba748 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -841,6 +841,8 @@ libsystemd_shared_la_SOURCES = \
src/shared/login-shared.h \
src/shared/ring.c \
src/shared/ring.h \
+ src/shared/barrier.c \
+ src/shared/barrier.h \
src/shared/async.c \
src/shared/async.h \
src/shared/eventfd-util.c \
@@ -1251,6 +1253,7 @@ tests += \
test-ellipsize \
test-util \
test-ring \
+ test-barrier \
test-tmpfiles \
test-namespace \
test-date \
@@ -1421,6 +1424,12 @@ test_ring_SOURCES = \
test_ring_LDADD = \
libsystemd-core.la
+test_barrier_SOURCES = \
+ src/test/test-barrier.c
+
+test_barrier_LDADD = \
+ libsystemd-core.la
+
test_tmpfiles_SOURCES = \
src/test/test-tmpfiles.c
diff --git a/src/shared/barrier.c b/src/shared/barrier.c
new file mode 100644
index 0000000000..c198329cb0
--- /dev/null
+++ b/src/shared/barrier.c
@@ -0,0 +1,440 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+ This file is part of systemd.
+
+ Copyright 2014 David Herrmann <dh.herrmann@gmail.com>
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/eventfd.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "barrier.h"
+#include "macro.h"
+#include "util.h"
+
+/**
+ * Barriers
+ * This barrier implementation provides a simple synchronization method based
+ * on file-descriptors that can safely be used between threads and processes. A
+ * barrier object contains 2 shared counters based on eventfd. Both processes
+ * can now place barriers and wait for the other end to reach a random or
+ * specific barrier.
+ * Barriers are numbered, so you can either wait for the other end to reach any
+ * barrier or the last barrier that you placed. This way, you can use barriers
+ * for one-way *and* full synchronization. Note that even-though barriers are
+ * numbered, these numbers are internal and recycled once both sides reached the
+ * same barrier (implemented as a simple signed counter). It is thus not
+ * possible to address barriers by their ID.
+ *
+ * Barrier-API: Both ends can place as many barriers via barrier_place() as
+ * they want and each pair of barriers on both sides will be implicitly linked.
+ * Each side can use the barrier_wait/sync_*() family of calls to wait for the
+ * other side to place a specific barrier. barrier_wait_next() waits until the
+ * other side calls barrier_place(). No links between the barriers are
+ * considered and this simply serves as most basic asynchronous barrier.
+ * barrier_sync_next() is like barrier_wait_next() and waits for the other side
+ * to place their next barrier via barrier_place(). However, it only waits for
+ * barriers that are linked to a barrier we already placed. If the other side
+ * already placed more barriers than we did, barrier_sync_next() returns
+ * immediately.
+ * barrier_sync() extends barrier_sync_next() and waits until the other end
+ * placed as many barriers via barrier_place() as we did. If they already placed
+ * as many as we did (or more), it returns immediately.
+ *
+ * Additionally to basic barriers, an abortion event is available.
+ * barrier_abort() places an abortion event that cannot be undone. An abortion
+ * immediately cancels all placed barriers and replaces them. Any running and
+ * following wait/sync call besides barrier_wait_abortion() will immediately
+ * return false on both sides (otherwise, they always return true).
+ * barrier_abort() can be called multiple times on both ends and will be a
+ * no-op if already called on this side.
+ * barrier_wait_abortion() can be used to wait for the other side to call
+ * barrier_abort() and is the only wait/sync call that does not return
+ * immediately if we aborted outself. It only returns once the other side
+ * called barrier_abort().
+ *
+ * Barriers can be used for in-process and inter-process synchronization.
+ * However, for in-process synchronization you could just use mutexes.
+ * Therefore, main target is IPC and we require both sides to *not* share the FD
+ * table. If that's given, barriers provide target tracking: If the remote side
+ * exit()s, an abortion event is implicitly queued on the other side. This way,
+ * a sync/wait call will be woken up if the remote side crashed or exited
+ * unexpectedly. However, note that these abortion events are only queued if the
+ * barrier-queue has been drained. Therefore, it is safe to place a barrier and
+ * exit. The other side can safely wait on the barrier even though the exit
+ * queued an abortion event. Usually, the abortion event would overwrite the
+ * barrier, however, that's not true for exit-abortion events. Those are only
+ * queued if the barrier-queue is drained (thus, the receiving side has placed
+ * more barriers than the remote side).
+ */
+
+/**
+ * barrier_init() - Initialize a barrier object
+ * @obj: barrier to initialize
+ *
+ * This initializes a barrier object. The caller is responsible of allocating
+ * the memory and keeping it valid. The memory does not have to be zeroed
+ * beforehand.
+ * Two eventfd objects are allocated for each barrier. If allocation fails, an
+ * error is returned.
+ *
+ * If this function fails, the barrier is reset to an invalid state so it is
+ * safe to call barrier_destroy() on the object regardless whether the
+ * initialization succeeded or not.
+ *
+ * The caller is responsible to destroy the object via barrier_destroy() before
+ * releasing the underlying memory.
+ *
+ * Returns: 0 on success, negative error code on failure.
+ */
+int barrier_init(Barrier *obj) {
+ _cleanup_(barrier_destroy) Barrier b = { };
+ int r;
+
+ assert_return(obj, -EINVAL);
+
+ b.me = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK);
+ if (b.me < 0)
+ return -errno;
+
+ b.them = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK);
+ if (b.them < 0)
+ return -errno;
+
+ r = pipe2(b.pipe, O_CLOEXEC | O_NONBLOCK);
+ if (r < 0)
+ return -errno;
+
+ memcpy(obj, &b, sizeof(b));
+ zero(b);
+ return 0;
+}
+
+/**
+ * barrier_destroy() - Destroy a barrier object
+ * @b: barrier to destroy or NULL
+ *
+ * This destroys a barrier object that has previously been initialized via
+ * barrier_init(). The object is released and reset to invalid state.
+ * Therefore, it is safe to call barrier_destroy() multiple times or even if
+ * barrier_init() failed. However, you must not call barrier_destroy() if you
+ * never called barrier_init() on the object before.
+ *
+ * It is safe to initialize a barrier via zero() / memset(.., 0, ...). Even
+ * though it has embedded FDs, barrier_destroy() can deal with zeroed objects
+ * just fine.
+ *
+ * If @b is NULL, this is a no-op.
+ */
+void barrier_destroy(Barrier *b) {
+ if (!b)
+ return;
+
+ /* @me and @them cannot be both FD 0. Lets be pedantic and check the
+ * pipes and barriers, too. If all are 0, the object was zero()ed and
+ * is invalid. This allows users to use zero(barrier) to reset the
+ * backing memory. */
+ if (b->me == 0 &&
+ b->them == 0 &&
+ b->pipe[0] == 0 &&
+ b->pipe[1] == 0 &&
+ b->barriers == 0)
+ return;
+
+ b->me = safe_close(b->me);
+ b->them = safe_close(b->them);
+ b->pipe[0] = safe_close(b->pipe[0]);
+ b->pipe[1] = safe_close(b->pipe[1]);
+ b->barriers = 0;
+}
+
+/**
+ * barrier_set_role() - Set the local role of the barrier
+ * @b: barrier to operate on
+ * @role: role to set on the barrier
+ *
+ * This sets the roles on a barrier object. This is needed to know which
+ * side of the barrier you're on. Usually, the parent creates the barrier via
+ * barrier_init() and then calls fork() or clone(). Therefore, the FDs are
+ * duplicated and the child retains the same barrier object.
+ *
+ * Both sides need to call barrier_set_role() after fork() or clone() are done.
+ * If this is not done, barriers will not work correctly.
+ *
+ * Note that barriers could be supported without fork() or clone(). However,
+ * this is currently not needed so it hasn't been implemented.
+ */
+void barrier_set_role(Barrier *b, unsigned int role) {
+ int fd;
+
+ assert(b);
+ assert(role == BARRIER_PARENT || role == BARRIER_CHILD);
+ /* make sure this is only called once */
+ assert(b->pipe[1] >= 0 && b->pipe[1] >= 0);
+
+ if (role == BARRIER_PARENT) {
+ b->pipe[1] = safe_close(b->pipe[1]);
+ } else {
+ b->pipe[0] = safe_close(b->pipe[0]);
+
+ /* swap me/them for children */
+ fd = b->me;
+ b->me = b->them;
+ b->them = fd;
+ }
+}
+
+/* places barrier; returns false if we aborted, otherwise true */
+static bool barrier_write(Barrier *b, uint64_t buf) {
+ ssize_t len;
+
+ /* prevent new sync-points if we already aborted */
+ if (barrier_i_aborted(b))
+ return false;
+
+ do {
+ len = write(b->me, &buf, sizeof(buf));
+ } while (len < 0 && (errno == EAGAIN || errno == EINTR));
+
+ if (len != sizeof(buf))
+ goto error;
+
+ /* lock if we aborted */
+ if (buf >= (uint64_t)BARRIER_ABORTION) {
+ if (barrier_they_aborted(b))
+ b->barriers = BARRIER_WE_ABORTED;
+ else
+ b->barriers = BARRIER_I_ABORTED;
+ } else if (!barrier_is_aborted(b)) {
+ b->barriers += buf;
+ }
+
+ return !barrier_i_aborted(b);
+
+error:
+ /* If there is an unexpected error, we have to make this fatal. There
+ * is no way we can recover from sync-errors. Therefore, we close the
+ * pipe-ends and treat this as abortion. The other end will notice the
+ * pipe-close and treat it as abortion, too. */
+
+ b->pipe[0] = safe_close(b->pipe[0]);
+ b->pipe[1] = safe_close(b->pipe[1]);
+ b->barriers = BARRIER_WE_ABORTED;
+ return false;
+}
+
+/* waits for barriers; returns false if they aborted, otherwise true */
+static bool barrier_read(Barrier *b, int64_t comp) {
+ uint64_t buf;
+ ssize_t len;
+ struct pollfd pfd[2] = { };
+ int r;
+
+ if (barrier_they_aborted(b))
+ return false;
+
+ while (b->barriers > comp) {
+ pfd[0].fd = (b->pipe[0] >= 0) ? b->pipe[0] : b->pipe[1];
+ pfd[0].events = POLLHUP;
+ pfd[0].revents = 0;
+ pfd[1].fd = b->them;
+ pfd[1].events = POLLIN;
+ pfd[1].revents = 0;
+
+ r = poll(pfd, 2, -1);
+ if (r < 0 && (errno == EAGAIN || errno == EINTR))
+ continue;
+ else if (r < 0)
+ goto error;
+
+ if (pfd[1].revents) {
+ /* events on @them signal us new data */
+ len = read(b->them, &buf, sizeof(buf));
+ if (len < 0 && (errno == EAGAIN || errno == EINTR))
+ continue;
+
+ if (len != sizeof(buf))
+ goto error;
+ } else if (pfd[0].revents & (POLLHUP | POLLERR | POLLNVAL)) {
+ /* POLLHUP on the pipe tells us the other side exited.
+ * We treat this as implicit abortion. But we only
+ * handle it if there's no event on the eventfd. This
+ * guarantees that exit-abortions do not overwrite real
+ * barriers. */
+ buf = BARRIER_ABORTION;
+ }
+
+ /* lock if they aborted */
+ if (buf >= (uint64_t)BARRIER_ABORTION) {
+ if (barrier_i_aborted(b))
+ b->barriers = BARRIER_WE_ABORTED;
+ else
+ b->barriers = BARRIER_THEY_ABORTED;
+ } else if (!barrier_is_aborted(b)) {
+ b->barriers -= buf;
+ }
+ }
+
+ return !barrier_they_aborted(b);
+
+error:
+ /* If there is an unexpected error, we have to make this fatal. There
+ * is no way we can recover from sync-errors. Therefore, we close the
+ * pipe-ends and treat this as abortion. The other end will notice the
+ * pipe-close and treat it as abortion, too. */
+
+ b->pipe[0] = safe_close(b->pipe[0]);
+ b->pipe[1] = safe_close(b->pipe[1]);
+ b->barriers = BARRIER_WE_ABORTED;
+ return false;
+}
+
+/**
+ * barrier_place() - Place a new barrier
+ * @b: barrier object
+ *
+ * This places a new barrier on the barrier object. If either side already
+ * aborted, this is a no-op and returns "false". Otherwise, the barrier is
+ * placed and this returns "true".
+ *
+ * Returns: true if barrier was placed, false if either side aborted.
+ */
+bool barrier_place(Barrier *b) {
+ assert(b);
+
+ if (barrier_is_aborted(b))
+ return false;
+
+ barrier_write(b, BARRIER_SINGLE);
+ return true;
+}
+
+/**
+ * barrier_abort() - Abort the synchronization
+ * @b: barrier object to abort
+ *
+ * This aborts the barrier-synchronization. If barrier_abort() was already
+ * called on this side, this is a no-op. Otherwise, the barrier is put into the
+ * ABORT-state and will stay there. The other side is notified about the
+ * abortion. Any following attempt to place normal barriers or to wait on normal
+ * barriers will return immediately as "false".
+ *
+ * You can wait for the other side to call barrier_abort(), too. Use
+ * barrier_wait_abortion() for that.
+ *
+ * Returns: false if the other side already aborted, true otherwise.
+ */
+bool barrier_abort(Barrier *b) {
+ assert(b);
+
+ barrier_write(b, BARRIER_ABORTION);
+ return !barrier_they_aborted(b);
+}
+
+/**
+ * barrier_wait_next() - Wait for the next barrier of the other side
+ * @b: barrier to operate on
+ *
+ * This waits until the other side places its next barrier. This is independent
+ * of any barrier-links and just waits for any next barrier of the other side.
+ *
+ * If either side aborted, this returns false.
+ *
+ * Returns: false if either side aborted, true otherwise.
+ */
+bool barrier_wait_next(Barrier *b) {
+ assert(b);
+
+ if (barrier_is_aborted(b))
+ return false;
+
+ barrier_read(b, b->barriers - 1);
+ return !barrier_is_aborted(b);
+}
+
+/**
+ * barrier_wait_abortion() - Wait for the other side to abort
+ * @b: barrier to operate on
+ *
+ * This waits until the other side called barrier_abort(). This can be called
+ * regardless whether the local side already called barrier_abort() or not.
+ *
+ * If the other side has already aborted, this returns immediately.
+ *
+ * Returns: false if the local side aborted, true otherwise.
+ */
+bool barrier_wait_abortion(Barrier *b) {
+ assert(b);
+
+ barrier_read(b, BARRIER_THEY_ABORTED);
+ return !barrier_i_aborted(b);
+}
+
+/**
+ * barrier_sync_next() - Wait for the other side to place a next linked barrier
+ * @b: barrier to operate on
+ *
+ * This is like barrier_wait_next() and waits for the other side to call
+ * barrier_place(). However, this only waits for linked barriers. That means, if
+ * the other side already placed more barriers than (or as much as) we did, this
+ * returns immediately instead of waiting.
+ *
+ * If either side aborted, this returns false.
+ *
+ * Returns: false if either side aborted, true otherwise.
+ */
+bool barrier_sync_next(Barrier *b) {
+ assert(b);
+
+ if (barrier_is_aborted(b))
+ return false;
+
+ barrier_read(b, MAX((int64_t)0, b->barriers - 1));
+ return !barrier_is_aborted(b);
+}
+
+/**
+ * barrier_sync() - Wait for the other side to place as many barriers as we did
+ * @b: barrier to operate on
+ *
+ * This is like barrier_sync_next() but waits for the other side to call
+ * barrier_place() as often as we did (in total). If they already placed as much
+ * as we did (or more), this returns immediately instead of waiting.
+ *
+ * If either side aborted, this returns false.
+ *
+ * Returns: false if either side aborted, true otherwise.
+ */
+bool barrier_sync(Barrier *b) {
+ assert(b);
+
+ if (barrier_is_aborted(b))
+ return false;
+
+ barrier_read(b, 0);
+ return !barrier_is_aborted(b);
+}
diff --git a/src/shared/barrier.h b/src/shared/barrier.h
new file mode 100644
index 0000000000..7f76ec7910
--- /dev/null
+++ b/src/shared/barrier.h
@@ -0,0 +1,92 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+ This file is part of systemd.
+
+ Copyright 2014 David Herrmann <dh.herrmann@gmail.com>
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <inttypes.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include "macro.h"
+#include "util.h"
+
+/* See source file for an API description. */
+
+typedef struct Barrier Barrier;
+
+enum {
+ BARRIER_SINGLE = 1LL,
+ BARRIER_ABORTION = INT64_MAX,
+
+ /* bias values to store state; keep @WE < @THEY < @I */
+ BARRIER_BIAS = INT64_MIN,
+ BARRIER_WE_ABORTED = BARRIER_BIAS + 1LL,
+ BARRIER_THEY_ABORTED = BARRIER_BIAS + 2LL,
+ BARRIER_I_ABORTED = BARRIER_BIAS + 3LL,
+};
+
+enum {
+ BARRIER_PARENT,
+ BARRIER_CHILD,
+};
+
+struct Barrier {
+ int me;
+ int them;
+ int pipe[2];
+ int64_t barriers;
+};
+
+int barrier_init(Barrier *obj);
+void barrier_destroy(Barrier *b);
+
+void barrier_set_role(Barrier *b, unsigned int role);
+
+bool barrier_place(Barrier *b);
+bool barrier_abort(Barrier *b);
+
+bool barrier_wait_next(Barrier *b);
+bool barrier_wait_abortion(Barrier *b);
+bool barrier_sync_next(Barrier *b);
+bool barrier_sync(Barrier *b);
+
+static inline bool barrier_i_aborted(Barrier *b) {
+ return b->barriers == BARRIER_I_ABORTED || b->barriers == BARRIER_WE_ABORTED;
+}
+
+static inline bool barrier_they_aborted(Barrier *b) {
+ return b->barriers == BARRIER_THEY_ABORTED || b->barriers == BARRIER_WE_ABORTED;
+}
+
+static inline bool barrier_we_aborted(Barrier *b) {
+ return b->barriers == BARRIER_WE_ABORTED;
+}
+
+static inline bool barrier_is_aborted(Barrier *b) {
+ return b->barriers == BARRIER_I_ABORTED || b->barriers == BARRIER_THEY_ABORTED || b->barriers == BARRIER_WE_ABORTED;
+}
+
+static inline bool barrier_place_and_sync(Barrier *b) {
+ barrier_place(b);
+ return barrier_sync(b);
+}
diff --git a/src/test/test-barrier.c b/src/test/test-barrier.c
new file mode 100644
index 0000000000..640e508679
--- /dev/null
+++ b/src/test/test-barrier.c
@@ -0,0 +1,460 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+ This file is part of systemd.
+
+ Copyright 2014 David Herrmann <dh.herrmann@gmail.com>
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+/*
+ * IPC barrier tests
+ * These tests verify the correct behavior of the IPC Barrier implementation.
+ * Note that the tests use alarm-timers to verify dead-locks and timeouts. These
+ * might not work on slow machines where 20ms are too short to perform specific
+ * operations (though, very unlikely). In case that turns out true, we have to
+ * increase it at the slightly cost of lengthen test-duration on other machines.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "barrier.h"
+#include "def.h"
+#include "util.h"
+
+/* 20ms to test deadlocks; All timings use multiples of this constant as
+ * alarm/sleep timers. If this timeout is too small for slow machines to perform
+ * the requested operations, we have to increase it. On an i7 this works fine
+ * with 1ms base-time, so 20ms should be just fine for everyone. */
+#define BASE_TIME 20
+
+static void malarm(unsigned long msecs) {
+ struct itimerval v = { };
+
+ timeval_store(&v.it_value, msecs * USEC_PER_MSEC);
+ assert_se(setitimer(ITIMER_REAL, &v, NULL) >= 0);
+}
+
+static void msleep(unsigned long msecs) {
+ assert_se(msecs < MSEC_PER_SEC);
+ usleep(msecs * USEC_PER_MSEC);
+}
+
+#define TEST_BARRIER(_FUNCTION, _CHILD_CODE, _WAIT_CHILD, _PARENT_CODE, _WAIT_PARENT) \
+ static void _FUNCTION(void) { \
+ Barrier b; \
+ pid_t pid1, pid2; \
+ \
+ assert_se(barrier_init(&b) >= 0); \
+ \
+ pid1 = fork(); \
+ assert_se(pid1 >= 0); \
+ if (pid1 == 0) { \
+ barrier_set_role(&b, BARRIER_CHILD); \
+ { _CHILD_CODE; } \
+ exit(42); \
+ } \
+ \
+ pid2 = fork(); \
+ assert_se(pid2 >= 0); \
+ if (pid2 == 0) { \
+ barrier_set_role(&b, BARRIER_PARENT); \
+ { _PARENT_CODE; } \
+ exit(42); \
+ } \
+ \
+ barrier_destroy(&b); \
+ malarm(999); \
+ { _WAIT_CHILD; } \
+ { _WAIT_PARENT; } \
+ malarm(0); \
+ }
+
+#define TEST_BARRIER_WAIT_SUCCESS(_pid) \
+ ({ \
+ int pidr, status; \
+ pidr = waitpid(_pid, &status, 0); \
+ assert_se(pidr == _pid); \
+ assert_se(WIFEXITED(status)); \
+ assert_se(WEXITSTATUS(status) == 42); \
+ })
+
+#define TEST_BARRIER_WAIT_ALARM(_pid) \
+ ({ \
+ int pidr, status; \
+ pidr = waitpid(_pid, &status, 0); \
+ assert_se(pidr == _pid); \
+ assert_se(WIFSIGNALED(status)); \
+ assert_se(WTERMSIG(status) == SIGALRM); \
+ })
+
+/*
+ * Test basic sync points
+ * This places a barrier in both processes and waits synchronously for them.
+ * The timeout makes sure the sync works as expected. The msleep() on one side
+ * makes sure the exit of the parent does not overwrite previous barriers. Due
+ * to the msleep(), we know that the parent already exited, thus there's a
+ * pending HUP on the pipe. However, the barrier_sync() prefers reads on the
+ * eventfd, thus we can safely wait on the barrier.
+ */
+TEST_BARRIER(test_barrier_sync,
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_place(&b));
+ msleep(BASE_TIME * 2);
+ assert_se(barrier_sync(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_place(&b));
+ assert_se(barrier_sync(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test wait_next()
+ * This places a barrier in the parent and syncs on it. The child sleeps while
+ * the parent places the barrier and then waits for a barrier. The wait will
+ * succeed as the child hasn't read the parent's barrier, yet. The following
+ * barrier and sync synchronize the exit.
+ */
+TEST_BARRIER(test_barrier_wait_next,
+ ({
+ msleep(100);
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_wait_next(&b));
+ assert_se(barrier_place(&b));
+ assert_se(barrier_sync(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ malarm(400);
+ assert_se(barrier_place(&b));
+ assert_se(barrier_sync(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test wait_next() multiple times
+ * This places two barriers in the parent and waits for the child to exit. The
+ * child sleeps 20ms so both barriers _should_ be in place. It then waits for
+ * the parent to place the next barrier twice. The first call will fetch both
+ * barriers and return. However, the second call will stall as the parent does
+ * not place a 3rd barrier (the sleep caught two barriers). wait_next() is does
+ * not look at barrier-links so this stall is expected. Thus this test times
+ * out.
+ */
+TEST_BARRIER(test_barrier_wait_next_twice,
+ ({
+ msleep(BASE_TIME);
+ malarm(BASE_TIME);
+ assert_se(barrier_wait_next(&b));
+ assert_se(barrier_wait_next(&b));
+ assert_se(0);
+ }),
+ TEST_BARRIER_WAIT_ALARM(pid1),
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_place(&b));
+ assert_se(barrier_place(&b));
+ msleep(BASE_TIME * 2);
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test wait_next() with local barriers
+ * This is the same as test_barrier_wait_next_twice, but places local barriers
+ * between both waits. This does not have any effect on the wait so it times out
+ * like the other test.
+ */
+TEST_BARRIER(test_barrier_wait_next_twice_local,
+ ({
+ msleep(BASE_TIME);
+ malarm(BASE_TIME);
+ assert_se(barrier_wait_next(&b));
+ assert_se(barrier_place(&b));
+ assert_se(barrier_place(&b));
+ assert_se(barrier_wait_next(&b));
+ assert_se(0);
+ }),
+ TEST_BARRIER_WAIT_ALARM(pid1),
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_place(&b));
+ assert_se(barrier_place(&b));
+ msleep(BASE_TIME * 2);
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test wait_next() with sync_next()
+ * This is again the same as test_barrier_wait_next_twice but uses a
+ * synced wait as the second wait. This works just fine because the local state
+ * has no barriers placed, therefore, the remote is always in sync.
+ */
+TEST_BARRIER(test_barrier_wait_next_twice_sync,
+ ({
+ msleep(BASE_TIME);
+ malarm(BASE_TIME);
+ assert_se(barrier_wait_next(&b));
+ assert_se(barrier_sync_next(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_place(&b));
+ assert_se(barrier_place(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test wait_next() with sync_next() and local barriers
+ * This is again the same as test_barrier_wait_next_twice_local but uses a
+ * synced wait as the second wait. This works just fine because the local state
+ * is in sync with the remote.
+ */
+TEST_BARRIER(test_barrier_wait_next_twice_local_sync,
+ ({
+ msleep(BASE_TIME);
+ malarm(BASE_TIME);
+ assert_se(barrier_wait_next(&b));
+ assert_se(barrier_place(&b));
+ assert_se(barrier_place(&b));
+ assert_se(barrier_sync_next(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_place(&b));
+ assert_se(barrier_place(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test sync_next() and sync()
+ * This tests sync_*() synchronizations and makes sure they work fine if the
+ * local state is behind the remote state.
+ */
+TEST_BARRIER(test_barrier_sync_next,
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_sync_next(&b));
+ assert_se(barrier_sync(&b));
+ assert_se(barrier_place(&b));
+ assert_se(barrier_place(&b));
+ assert_se(barrier_sync_next(&b));
+ assert_se(barrier_sync_next(&b));
+ assert_se(barrier_sync(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ malarm(BASE_TIME * 10);
+ msleep(BASE_TIME);
+ assert_se(barrier_place(&b));
+ assert_se(barrier_place(&b));
+ assert_se(barrier_sync(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test sync_next() and sync() with local barriers
+ * This tests timeouts if sync_*() is used if local barriers are placed but the
+ * remote didn't place any.
+ */
+TEST_BARRIER(test_barrier_sync_next_local,
+ ({
+ malarm(BASE_TIME);
+ assert_se(barrier_place(&b));
+ assert_se(barrier_sync_next(&b));
+ assert_se(0);
+ }),
+ TEST_BARRIER_WAIT_ALARM(pid1),
+ ({
+ msleep(BASE_TIME * 2);
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test sync_next() and sync() with local barriers and abortion
+ * This is the same as test_barrier_sync_next_local but aborts the sync in the
+ * parent. Therefore, the sync_next() succeeds just fine due to the abortion.
+ */
+TEST_BARRIER(test_barrier_sync_next_local_abort,
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_place(&b));
+ assert_se(!barrier_sync_next(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ assert_se(barrier_abort(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test matched wait_abortion()
+ * This runs wait_abortion() with remote abortion.
+ */
+TEST_BARRIER(test_barrier_wait_abortion,
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_wait_abortion(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ assert_se(barrier_abort(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test unmatched wait_abortion()
+ * This runs wait_abortion() without any remote abortion going on. It thus must
+ * timeout.
+ */
+TEST_BARRIER(test_barrier_wait_abortion_unmatched,
+ ({
+ malarm(BASE_TIME);
+ assert_se(barrier_wait_abortion(&b));
+ assert_se(0);
+ }),
+ TEST_BARRIER_WAIT_ALARM(pid1),
+ ({
+ msleep(BASE_TIME * 2);
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test matched wait_abortion() with local abortion
+ * This runs wait_abortion() with local and remote abortion.
+ */
+TEST_BARRIER(test_barrier_wait_abortion_local,
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_abort(&b));
+ assert_se(!barrier_wait_abortion(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ assert_se(barrier_abort(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test unmatched wait_abortion() with local abortion
+ * This runs wait_abortion() with only local abortion. This must time out.
+ */
+TEST_BARRIER(test_barrier_wait_abortion_local_unmatched,
+ ({
+ malarm(BASE_TIME);
+ assert_se(barrier_abort(&b));
+ assert_se(!barrier_wait_abortion(&b));
+ assert_se(0);
+ }),
+ TEST_BARRIER_WAIT_ALARM(pid1),
+ ({
+ msleep(BASE_TIME * 2);
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test child exit
+ * Place barrier and sync with the child. The child only exits()s, which should
+ * cause an implicit abortion and wake the parent.
+ */
+TEST_BARRIER(test_barrier_exit,
+ ({
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ malarm(BASE_TIME * 10);
+ assert_se(barrier_place(&b));
+ assert_se(!barrier_sync(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+/*
+ * Test child exit with sleep
+ * Same as test_barrier_exit but verifies the test really works due to the
+ * child-exit. We add a usleep() which triggers the alarm in the parent and
+ * causes the test to time out.
+ */
+TEST_BARRIER(test_barrier_no_exit,
+ ({
+ msleep(BASE_TIME * 2);
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ malarm(BASE_TIME);
+ assert_se(barrier_place(&b));
+ assert_se(!barrier_sync(&b));
+ }),
+ TEST_BARRIER_WAIT_ALARM(pid2));
+
+/*
+ * Test pending exit against sync
+ * The parent places a barrier *and* exits. The 20ms wait in the child
+ * guarantees both are pending. However, our logic prefers pending barriers over
+ * pending exit-abortions (unlike normal abortions), thus the wait_next() must
+ * succeed, same for the sync_next() as our local barrier-count is smaller than
+ * the remote. Once we place a barrier our count is equal, so the sync still
+ * succeeds. Only if we place one more barrier, we're ahead of the remote, thus
+ * we will fail due to HUP on the pipe.
+ */
+TEST_BARRIER(test_barrier_pending_exit,
+ ({
+ malarm(BASE_TIME * 4);
+ msleep(BASE_TIME * 2);
+ assert_se(barrier_wait_next(&b));
+ assert_se(barrier_sync_next(&b));
+ assert_se(barrier_place(&b));
+ assert_se(barrier_sync_next(&b));
+ assert_se(barrier_place(&b));
+ assert_se(!barrier_sync_next(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid1),
+ ({
+ assert_se(barrier_place(&b));
+ }),
+ TEST_BARRIER_WAIT_SUCCESS(pid2));
+
+int main(int argc, char *argv[]) {
+ log_parse_environment();
+ log_open();
+
+ test_barrier_sync();
+ test_barrier_wait_next();
+ test_barrier_wait_next_twice();
+ test_barrier_wait_next_twice_sync();
+ test_barrier_wait_next_twice_local();
+ test_barrier_wait_next_twice_local_sync();
+ test_barrier_sync_next();
+ test_barrier_sync_next_local();
+ test_barrier_sync_next_local_abort();
+ test_barrier_wait_abortion();
+ test_barrier_wait_abortion_unmatched();
+ test_barrier_wait_abortion_local();
+ test_barrier_wait_abortion_local_unmatched();
+ test_barrier_exit();
+ test_barrier_no_exit();
+ test_barrier_pending_exit();
+
+ return 0;
+}