From d653d0886c607be53048e81176a6c1f6ed6e6034 Mon Sep 17 00:00:00 2001
From: godzie44 <godzie@yandex.ru>
Date: Mon, 22 May 2023 13:59:28 +0300
Subject: [PATCH] cbus: introduce lcpipe - light cpipe
Introduced a new type of cbus pipe - lcpipe. The current pipe in the
cbus - cpipe, has a number of limitations, first of all - the cpipe
cannot be used from the 3rd party threads, cpipe only works as a channel
between two cords. That why lcpipe is needed. Its main responsibility -
create channel between any thread and tarantool cord.
Internally lcpipe is a cpipe, but:
- on flush triggers removed, cause triggers use thread-local mem-pool,
this is not possible on a third party thread
- producer event loop removed, cause there is no libev event loop in
third party thread
Also, lcpipe interface is exported to the outside world.
NO_DOC=core feature
---
changelogs/unreleased/fork-3-lcpipe.md | 8 +
extra/exports | 11 ++
src/lib/core/cbus.c | 204 +++++++++++++++++++++--
src/lib/core/cbus.h | 82 ++++++++++
test/unit/CMakeLists.txt | 3 +
test/unit/cbus_lcpipe.c | 218 +++++++++++++++++++++++++
6 files changed, 513 insertions(+), 13 deletions(-)
create mode 100644 changelogs/unreleased/fork-3-lcpipe.md
create mode 100644 test/unit/cbus_lcpipe.c
diff --git a/changelogs/unreleased/fork-3-lcpipe.md b/changelogs/unreleased/fork-3-lcpipe.md
new file mode 100644
index 0000000000..e8ebc76ef7
--- /dev/null
+++ b/changelogs/unreleased/fork-3-lcpipe.md
@@ -0,0 +1,8 @@
+## feature/build
+
+* export cbus interface:
+ * cbus_endpoint_new
+ * cbus_endpoint_delete
+ * cbus_loop
+ * cbus_process
+* add new type of cbus pipe: lcpipe. Lcpipe main purpose - send messages from 3rtd party tread into tarantool cord
diff --git a/extra/exports b/extra/exports
index d59221142f..b4330ea90d 100644
--- a/extra/exports
+++ b/extra/exports
@@ -624,3 +624,14 @@ fiber_channel_get_msg_timeout
fiber_channel_has_readers
fiber_channel_has_writers
fiber_channel_new
+
+# picodata cbus
+cbus_endpoint_delete
+cbus_endpoint_new
+cbus_loop
+cbus_process
+lcpipe_delete
+lcpipe_flush_input
+lcpipe_new
+lcpipe_push
+lcpipe_push_now
diff --git a/src/lib/core/cbus.c b/src/lib/core/cbus.c
index 4724dd6468..81fc0f615d 100644
--- a/src/lib/core/cbus.c
+++ b/src/lib/core/cbus.c
@@ -87,6 +87,25 @@ static void
cpipe_flush_cb(ev_loop * /* loop */, struct ev_async *watcher,
int /* events */);
+/**
+ * Acquire cbus endpoint, identified by consumer name.
+ * The call returns when the consumer has joined the bus.
+ */
+static inline void
+acquire_consumer(struct cbus_endpoint **pipe_endpoint, const char *name)
+{
+ tt_pthread_mutex_lock(&cbus.mutex);
+ struct cbus_endpoint *endpoint =
+ cbus_find_endpoint_locked(&cbus, name);
+ while (endpoint == NULL) {
+ tt_pthread_cond_wait(&cbus.cond, &cbus.mutex);
+ endpoint = cbus_find_endpoint_locked(&cbus, name);
+ }
+ *pipe_endpoint = endpoint;
+ ++(*pipe_endpoint)->n_pipes;
+ tt_pthread_mutex_unlock(&cbus.mutex);
+}
+
void
cpipe_create(struct cpipe *pipe, const char *consumer)
{
@@ -100,16 +119,7 @@ cpipe_create(struct cpipe *pipe, const char *consumer)
pipe->flush_input.data = pipe;
rlist_create(&pipe->on_flush);
- tt_pthread_mutex_lock(&cbus.mutex);
- struct cbus_endpoint *endpoint =
- cbus_find_endpoint_locked(&cbus, consumer);
- while (endpoint == NULL) {
- tt_pthread_cond_wait(&cbus.cond, &cbus.mutex);
- endpoint = cbus_find_endpoint_locked(&cbus, consumer);
- }
- pipe->endpoint = endpoint;
- ++pipe->endpoint->n_pipes;
- tt_pthread_mutex_unlock(&cbus.mutex);
+ acquire_consumer(&pipe->endpoint, consumer);
}
struct cmsg_poison {
@@ -177,6 +187,145 @@ cpipe_destroy(struct cpipe *pipe)
TRASH(pipe);
}
+struct lcpipe *
+lcpipe_new(const char *consumer)
+{
+ struct lcpipe *pipe = xmalloc(sizeof(*pipe));
+
+ stailq_create(&pipe->input);
+
+ pipe->n_input = 0;
+ pipe->max_input = INT_MAX;
+
+ acquire_consumer(&pipe->endpoint, consumer);
+
+ return pipe;
+}
+
+/**
+ * Flush all staged messages into consumer output and wake up it after.
+ */
+static void
+lcpipe_flush(struct lcpipe *pipe)
+{
+ struct cbus_endpoint *endpoint = pipe->endpoint;
+ if (pipe->n_input == 0)
+ return;
+
+ /* Trigger task processing when the queue becomes non-empty. */
+ bool output_was_empty;
+
+ /*
+ * We need to set a thread cancellation guard, because
+ * another thread may cancel the current thread
+ * (write() is a cancellation point in ev_async_send)
+ * and the activation of the ev_async watcher
+ * through ev_async_send will fail.
+ */
+
+ int old_cancel_state;
+ tt_pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old_cancel_state);
+
+ tt_pthread_mutex_lock(&endpoint->mutex);
+ output_was_empty = stailq_empty(&endpoint->output);
+ /** Flush input */
+ stailq_concat(&endpoint->output, &pipe->input);
+ tt_pthread_mutex_unlock(&endpoint->mutex);
+
+ pipe->n_input = 0;
+ if (output_was_empty) {
+ /* Count statistics */
+ rmean_collect(cbus.stats, CBUS_STAT_EVENTS, 1);
+
+ ev_async_send(pipe->endpoint->consumer, &pipe->endpoint->async);
+ }
+
+ tt_pthread_setcancelstate(old_cancel_state, NULL);
+}
+
+void
+lcpipe_flush_input(struct lcpipe *pipe)
+{
+ /** Flush may be called with no input. */
+ if (pipe->n_input > 0) {
+ lcpipe_flush(pipe);
+ }
+}
+
+/**
+ * Insert message into pipe input queue.
+ */
+static inline void
+lcpipe_insert_input(struct lcpipe *pipe, struct cmsg *msg)
+{
+ assert(msg->hop->pipe == NULL);
+ stailq_add_tail_entry(&pipe->input, msg, fifo);
+ pipe->n_input++;
+ if (pipe->n_input >= pipe->max_input) {
+ lcpipe_flush(pipe);
+ }
+}
+
+void
+lcpipe_push(struct lcpipe *pipe, struct cmsg *msg)
+{
+ lcpipe_insert_input(pipe, msg);
+ assert(pipe->n_input < pipe->max_input);
+}
+
+void
+lcpipe_push_now(struct lcpipe *pipe, struct cmsg *msg)
+{
+ lcpipe_insert_input(pipe, msg);
+ assert(pipe->n_input < pipe->max_input);
+ lcpipe_flush(pipe);
+}
+
+void
+lcpipe_delete(struct lcpipe *pipe)
+{
+ /*
+ * The thread should not be canceled while mutex is locked.
+ * And everything else must be protected for consistency.
+ */
+ int old_cancel_state;
+ tt_pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old_cancel_state);
+
+ static const struct cmsg_hop route[1] = {
+ {cbus_endpoint_poison_f, NULL}
+ };
+
+ struct cbus_endpoint *endpoint = pipe->endpoint;
+ struct cmsg_poison *poison = xmalloc(sizeof(*poison));
+ cmsg_init(&poison->msg, route);
+ poison->endpoint = pipe->endpoint;
+ /*
+ * Avoid the general purpose lcpipe_insert_input() since
+ * we want to control the way the poison message is
+ * delivered.
+ */
+ tt_pthread_mutex_lock(&endpoint->mutex);
+ /* Flush input */
+ stailq_concat(&endpoint->output, &pipe->input);
+ pipe->n_input = 0;
+ /* Add the pipe shutdown message as the last one. */
+ stailq_add_tail_entry(&endpoint->output, poison, msg.fifo);
+ /* Count statistics */
+ rmean_collect(cbus.stats, CBUS_STAT_EVENTS, 1);
+ /*
+ * Keep the lock for the duration of ev_async_send():
+ * this will avoid a race condition between
+ * ev_async_send() and execution of the poison
+ * message, after which the endpoint may disappear.
+ */
+ ev_async_send(endpoint->consumer, &endpoint->async);
+ tt_pthread_mutex_unlock(&endpoint->mutex);
+
+ tt_pthread_setcancelstate(old_cancel_state, NULL);
+
+ free(pipe);
+}
+
static void
cbus_create(struct cbus *bus)
{
@@ -247,8 +396,21 @@ cbus_endpoint_create(struct cbus_endpoint *endpoint, const char *name,
}
int
-cbus_endpoint_destroy(struct cbus_endpoint *endpoint,
- void (*process_cb)(struct cbus_endpoint *endpoint))
+cbus_endpoint_new(struct cbus_endpoint **endpoint, const char *name)
+{
+ struct cbus_endpoint *new_endpoint = xmalloc(sizeof(*new_endpoint));
+ *endpoint = new_endpoint;
+
+ int err = cbus_endpoint_create(new_endpoint, name, fiber_schedule_cb,
+ fiber());
+ if (err)
+ free(new_endpoint);
+ return err;
+}
+
+static inline void
+cbus_endpoint_destroy_inner(struct cbus_endpoint *endpoint,
+ void (*process_cb)(struct cbus_endpoint *endpoint))
{
tt_pthread_mutex_lock(&cbus.mutex);
/*
@@ -263,7 +425,7 @@ cbus_endpoint_destroy(struct cbus_endpoint *endpoint,
process_cb(endpoint);
if (endpoint->n_pipes == 0 && stailq_empty(&endpoint->output))
break;
- fiber_cond_wait(&endpoint->cond);
+ fiber_cond_wait(&endpoint->cond);
}
/*
@@ -275,6 +437,22 @@ cbus_endpoint_destroy(struct cbus_endpoint *endpoint,
tt_pthread_mutex_destroy(&endpoint->mutex);
ev_async_stop(endpoint->consumer, &endpoint->async);
fiber_cond_destroy(&endpoint->cond);
+}
+
+int
+cbus_endpoint_delete(struct cbus_endpoint *endpoint)
+{
+ cbus_endpoint_destroy_inner(endpoint, cbus_process);
+ free(endpoint);
+ TRASH(endpoint);
+ return 0;
+}
+
+int
+cbus_endpoint_destroy(struct cbus_endpoint *endpoint,
+ void (*process_cb)(struct cbus_endpoint *endpoint))
+{
+ cbus_endpoint_destroy_inner(endpoint, process_cb);
TRASH(endpoint);
return 0;
}
diff --git a/src/lib/core/cbus.h b/src/lib/core/cbus.h
index 6b06312841..c7dd96bd88 100644
--- a/src/lib/core/cbus.h
+++ b/src/lib/core/cbus.h
@@ -299,6 +299,28 @@ int
cbus_endpoint_create(struct cbus_endpoint *endpoint, const char *name,
void (*fetch_cb)(ev_loop *, struct ev_watcher *, int), void *fetch_data);
+/**
+ * Allocate and initialize cbus endpoint.
+ * Endpoint initialized by ready for use defaults. Can be using by 3rtd party
+ * code.
+ * @param endpoint cbus endpoint dst
+ * @param name a destination name
+ * @retval 0 for success
+ * @retval 1 if endpoint with given name already registered
+ */
+int
+cbus_endpoint_new(struct cbus_endpoint **endpoint, const char *name);
+
+/**
+ * Delete cbus endpoint. Disconnect the cord from cbus and free endpoint data.
+ * @param endpoint cbus endpoint must have been allocated with a call to
+ * `cbus_endpoint_new`.
+ * @retval 0 for success
+ * @retval 1 if there is connected pipe or unhandled message`
+ */
+int
+cbus_endpoint_delete(struct cbus_endpoint *endpoint);
+
/**
* One round for message fetch and deliver */
void
@@ -453,6 +475,66 @@ cbus_unpair(struct cpipe *dest_pipe, struct cpipe *src_pipe,
void (*unpair_cb)(void *), void *unpair_arg,
void (*process_cb)(struct cbus_endpoint *));
+/**
+ * A uni-directional FIFO queue from any thread to cord.
+ * It is a light version of the cpipe, since some features are not needed for
+ * 3td party threads or they cannot be implemented.
+ *
+ */
+struct lcpipe {
+ /** Staging area for pushed messages */
+ struct stailq input;
+ /** Counters are useful for finer-grained scheduling. */
+ int n_input;
+ /**
+ * When pushing messages, keep the staged input size under
+ * this limit (speeds up message delivery and reduces
+ * latency, while still keeping the bus mutex cold enough).
+ */
+ int max_input;
+ /**
+ * The cbus endpoint at the destination cord to handle
+ * flushed messages.
+ */
+ struct cbus_endpoint *endpoint;
+};
+
+/**
+ * Create and initialize a pipe and connect it to the consumer.
+ * The call returns only when the consumer, identified by consumer name, has
+ * joined the bus.
+ **/
+struct lcpipe *
+lcpipe_new(const char *consumer);
+
+/**
+ * Destroy a pipe with freeing up occupied memory.
+ * @param pipe lcpipe must have been allocated with a call to `lcpipe_new`.
+ **/
+void
+lcpipe_delete(struct lcpipe *pipe);
+
+/**
+ * Flush all staged messages into the pipe and eventually to the
+ * consumer.
+ */
+void
+lcpipe_flush_input(struct lcpipe *pipe);
+
+/**
+ * Push a message into input queue without flushing.
+ * @param msg cbus message, pipe in message hop must be set at NULL.
+ */
+void
+lcpipe_push(struct lcpipe *pipe, struct cmsg *msg);
+
+/**
+ * Push a single message and flush input queue immediately.
+ * @param msg cbus message, pipe in message hop must be set at NULL.
+ */
+void
+lcpipe_push_now(struct lcpipe *pipe, struct cmsg *msg);
+
#if defined(__cplusplus)
} /* extern "C" */
#endif /* defined(__cplusplus) */
diff --git a/test/unit/CMakeLists.txt b/test/unit/CMakeLists.txt
index e14d37b409..2bf5f47693 100644
--- a/test/unit/CMakeLists.txt
+++ b/test/unit/CMakeLists.txt
@@ -261,6 +261,9 @@ create_unit_test(PREFIX cbus_call
LIBRARIES core unit stat
)
+add_executable(cbus_lcpipe.test cbus_lcpipe.c core_test_utils.c)
+target_link_libraries(cbus_lcpipe.test core unit stat)
+
include(CheckSymbolExists)
check_symbol_exists(__GLIBC__ features.h GLIBC_USED)
if (GLIBC_USED)
diff --git a/test/unit/cbus_lcpipe.c b/test/unit/cbus_lcpipe.c
new file mode 100644
index 0000000000..6682a191d2
--- /dev/null
+++ b/test/unit/cbus_lcpipe.c
@@ -0,0 +1,218 @@
+#define UNIT_TAP_COMPATIBLE 1
+#include "memory.h"
+#include "fiber.h"
+#include "cbus.h"
+#include "unit.h"
+#include "trigger.h"
+
+/**
+ * Test lcpipe message passing. lcpipe works with messages in two modes:
+ * 1) lcpipe_push_now - send message immediately
+ * 2) lcpipe_push - puts a message in a lcpipe without forwarding it.
+ * Forwarding must call explicitly by calling lcpipe_flush_input function.
+ */
+
+/** Counter of flush events. */
+static int flushed_cnt = 0;
+
+static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
+static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/** Common callbacks. {{{ ------------------------------------- */
+
+static void
+inc_counter_cb(struct cmsg *m)
+{
+ (void)m;
+ ++flushed_cnt;
+ note("flush event, counter: %d\n", flushed_cnt);
+}
+
+static void
+inc_counter_and_signal_cb(struct cmsg *m)
+{
+ inc_counter_cb(m);
+ tt_pthread_mutex_lock(&mutex);
+ tt_pthread_cond_signal(&cond);
+ tt_pthread_mutex_unlock(&mutex);
+}
+
+static void
+inc_counter_and_signal_then_cancel_cb(struct cmsg *m)
+{
+ inc_counter_and_signal_cb(m);
+ fiber_cancel(fiber());
+}
+
+/** }}} Common callbacks. ------------------------------------- */
+
+/**
+ * Test push a single message.
+ * {{{ -----------------------------------------------------------
+ */
+
+static void
+test_single_msg(struct lcpipe *pipe)
+{
+ note("\n*** Test single message ***\n");
+ static struct cmsg_hop test_event_route[] = {
+ { inc_counter_and_signal_cb, NULL },
+ };
+ static struct cmsg test_msg;
+ cmsg_init(&test_msg, test_event_route);
+
+ tt_pthread_mutex_lock(&mutex);
+
+ lcpipe_push_now(pipe, &test_msg);
+
+ tt_pthread_cond_wait(&cond, &mutex);
+ tt_pthread_mutex_unlock(&mutex);
+
+ is(flushed_cnt, 1, "1 flush after %s", __func__);
+}
+
+/** }}} Test single message. ---------------------------------- */
+
+/**
+ * Test insert a batch of messages and flush it.
+ * {{{ -----------------------------------------------------------
+ */
+
+static void
+test_batch_msg(struct lcpipe *pipe)
+{
+ note("\n*** Test batch of messages ***\n");
+ static struct cmsg_hop test_event_routes[][1] = {
+ {{inc_counter_cb, NULL}},
+ {{inc_counter_cb, NULL}},
+ {{inc_counter_cb, NULL}},
+ {{inc_counter_cb, NULL}},
+ {{inc_counter_and_signal_cb, NULL}},
+ };
+ static struct cmsg test_msg[5];
+ for (unsigned i = 0; i < 5; i++) {
+ cmsg_init(&test_msg[i], test_event_routes[i]);
+ lcpipe_push(pipe, &test_msg[i]);
+ }
+
+ tt_pthread_mutex_lock(&mutex);
+
+ lcpipe_flush_input(pipe);
+
+ tt_pthread_cond_wait(&cond, &mutex);
+ tt_pthread_mutex_unlock(&mutex);
+
+ is(flushed_cnt, 6, "6 flush after %s", __func__);
+}
+
+/** }}} Test a batch of messages. ---------------------------------- */
+
+/**
+ * Test sequence of lcpipe_push and lcpipe_push_now functions. lcpipe_push_now
+ * must release messages previously inserted by lcpipe_push function.
+ * {{{ -----------------------------------------------------------
+ */
+
+static void
+test_push_then_push_now(struct lcpipe *pipe)
+{
+ note("\n*** Test sequence of lcpipe_push and lcpipe_push_now ***\n");
+ static struct cmsg_hop test_event_route_1[] = {
+ { inc_counter_cb, NULL },
+ };
+ static struct cmsg test_msg_1;
+ cmsg_init(&test_msg_1, test_event_route_1);
+
+ static struct cmsg_hop test_event_route_2[] = {
+ { inc_counter_and_signal_then_cancel_cb, NULL },
+ };
+ static struct cmsg test_msg_2;
+ cmsg_init(&test_msg_2, test_event_route_2);
+
+ tt_pthread_mutex_lock(&mutex);
+
+ lcpipe_push(pipe, &test_msg_1);
+ lcpipe_push_now(pipe, &test_msg_2);
+
+ tt_pthread_cond_wait(&cond, &mutex);
+ tt_pthread_mutex_unlock(&mutex);
+
+ is(flushed_cnt, 8, "8 flush after %s", __func__);
+}
+
+/** }}} Test sequence of lcpipe_push and lcpipe_push_now functions. ------ */
+
+/** Worker routines. {{{ -------------------------------------- */
+
+static void *
+worker_f(void *data)
+{
+ char *name = (char *)data;
+
+ plan(3);
+ header();
+
+ note("start new worker, thread %s\n", name);
+
+ struct lcpipe *pipe = lcpipe_new("main");
+ test_single_msg(pipe);
+ test_batch_msg(pipe);
+ test_push_then_push_now(pipe);
+ lcpipe_delete(pipe);
+
+ int rc = check_plan();
+ pthread_exit((void *)(intptr_t)rc);
+}
+
+static void
+worker_start(pthread_t *handle)
+{
+ pthread_create(handle, NULL, worker_f, "X");
+}
+
+static int
+worker_stop(pthread_t handle)
+{
+ note("finish worker\n");
+ void *rc = NULL;
+ pthread_join(handle, &rc);
+ return (int)(intptr_t)rc;
+}
+
+/** }}} Worker routines. -------------------------------------- */
+
+static int
+main_f(va_list ap)
+{
+ (void)ap;
+ struct cbus_endpoint endpoint;
+ cbus_endpoint_create(&endpoint, "main", fiber_schedule_cb, fiber());
+ pthread_t th;
+ worker_start(&th);
+ cbus_loop(&endpoint);
+ int rc = worker_stop(th);
+ cbus_endpoint_destroy(&endpoint, cbus_process);
+ ev_break(loop(), EVBREAK_ALL);
+ return rc;
+}
+
+int
+main(void)
+{
+ memory_init();
+ fiber_init(fiber_c_invoke);
+ cbus_init();
+ struct fiber *main_fiber = fiber_new("main", main_f);
+ assert(main_fiber != NULL);
+ fiber_set_joinable(main_fiber, true);
+ fiber_wakeup(main_fiber);
+ ev_run(loop(), 0);
+ note("finish %s loop\n", __func__);
+ int rc = fiber_join(main_fiber);
+ cbus_free();
+ fiber_free();
+ memory_free();
+
+ footer();
+ return rc;
+}
--
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