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/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
#include <aws/io/future.h>
#include <aws/common/condition_variable.h>
#include <aws/common/mutex.h>
#include <aws/common/ref_count.h>
#include <aws/common/task_scheduler.h>
#include <aws/io/channel.h>
#include <aws/io/event_loop.h>
enum aws_future_type {
AWS_FUTURE_T_BY_VALUE,
AWS_FUTURE_T_BY_VALUE_WITH_CLEAN_UP,
AWS_FUTURE_T_POINTER,
AWS_FUTURE_T_POINTER_WITH_DESTROY,
AWS_FUTURE_T_POINTER_WITH_RELEASE,
};
struct aws_future_callback_data {
aws_future_callback_fn *fn;
void *user_data;
union aws_future_callback_union {
struct aws_event_loop *event_loop;
struct aws_channel *channel;
} u;
enum aws_future_callback_type {
AWS_FUTURE_IMMEDIATE_CALLBACK,
AWS_FUTURE_EVENT_LOOP_CALLBACK,
AWS_FUTURE_CHANNEL_CALLBACK,
} type;
};
/* When allocating aws_future<T> on the heap, we make 1 allocation containing:
* aws_future_impl followed by T */
struct aws_future_impl {
struct aws_allocator *alloc;
struct aws_ref_count ref_count;
struct aws_mutex lock;
struct aws_condition_variable wait_cvar;
struct aws_future_callback_data callback;
union {
aws_future_impl_result_clean_up_fn *clean_up;
aws_future_impl_result_destroy_fn *destroy;
aws_future_impl_result_release_fn *release;
} result_dtor;
int error_code;
/* sum of bit fields should be 32 */
#define BIT_COUNT_FOR_SIZEOF_RESULT 27
unsigned int sizeof_result : BIT_COUNT_FOR_SIZEOF_RESULT;
unsigned int type : 3; /* aws_future_type */
unsigned int is_done : 1;
unsigned int owns_result : 1;
};
static void s_future_impl_result_dtor(struct aws_future_impl *future, void *result_addr) {
switch (future->type) {
case AWS_FUTURE_T_BY_VALUE_WITH_CLEAN_UP: {
future->result_dtor.clean_up(result_addr);
break;
} break;
case AWS_FUTURE_T_POINTER_WITH_DESTROY: {
void *result = *(void **)result_addr;
if (result) {
future->result_dtor.destroy(result);
}
} break;
case AWS_FUTURE_T_POINTER_WITH_RELEASE: {
void *result = *(void **)result_addr;
if (result) {
future->result_dtor.release(result);
}
} break;
default:
break;
}
}
static void s_future_impl_destroy(void *user_data) {
struct aws_future_impl *future = user_data;
if (future->owns_result && !future->error_code) {
s_future_impl_result_dtor(future, aws_future_impl_get_result_address(future));
}
aws_condition_variable_clean_up(&future->wait_cvar);
aws_mutex_clean_up(&future->lock);
aws_mem_release(future->alloc, future);
}
static struct aws_future_impl *s_future_impl_new(struct aws_allocator *alloc, size_t sizeof_result) {
size_t total_size = sizeof(struct aws_future_impl) + sizeof_result;
struct aws_future_impl *future = aws_mem_calloc(alloc, 1, total_size);
future->alloc = alloc;
/* we store sizeof_result in a bit field, ensure the number will fit */
AWS_ASSERT(sizeof_result <= (UINT_MAX >> (32 - BIT_COUNT_FOR_SIZEOF_RESULT)));
future->sizeof_result = (unsigned int)sizeof_result;
aws_ref_count_init(&future->ref_count, future, s_future_impl_destroy);
aws_mutex_init(&future->lock);
aws_condition_variable_init(&future->wait_cvar);
return future;
}
struct aws_future_impl *aws_future_impl_new_by_value(struct aws_allocator *alloc, size_t sizeof_result) {
struct aws_future_impl *future = s_future_impl_new(alloc, sizeof_result);
future->type = AWS_FUTURE_T_BY_VALUE;
return future;
}
struct aws_future_impl *aws_future_impl_new_by_value_with_clean_up(
struct aws_allocator *alloc,
size_t sizeof_result,
aws_future_impl_result_clean_up_fn *result_clean_up) {
AWS_ASSERT(result_clean_up);
struct aws_future_impl *future = s_future_impl_new(alloc, sizeof_result);
future->type = AWS_FUTURE_T_BY_VALUE_WITH_CLEAN_UP;
future->result_dtor.clean_up = result_clean_up;
return future;
}
struct aws_future_impl *aws_future_impl_new_pointer(struct aws_allocator *alloc) {
struct aws_future_impl *future = s_future_impl_new(alloc, sizeof(void *));
future->type = AWS_FUTURE_T_POINTER;
return future;
}
struct aws_future_impl *aws_future_impl_new_pointer_with_destroy(
struct aws_allocator *alloc,
aws_future_impl_result_destroy_fn *result_destroy) {
AWS_ASSERT(result_destroy);
struct aws_future_impl *future = s_future_impl_new(alloc, sizeof(void *));
future->type = AWS_FUTURE_T_POINTER_WITH_DESTROY;
future->result_dtor.destroy = result_destroy;
return future;
}
struct aws_future_impl *aws_future_impl_new_pointer_with_release(
struct aws_allocator *alloc,
aws_future_impl_result_release_fn *result_release) {
AWS_ASSERT(result_release);
struct aws_future_impl *future = s_future_impl_new(alloc, sizeof(void *));
future->type = AWS_FUTURE_T_POINTER_WITH_RELEASE;
future->result_dtor.release = result_release;
return future;
}
struct aws_future_impl *aws_future_impl_release(struct aws_future_impl *future) {
if (future != NULL) {
aws_ref_count_release(&future->ref_count);
}
return NULL;
}
struct aws_future_impl *aws_future_impl_acquire(struct aws_future_impl *future) {
if (future != NULL) {
aws_ref_count_acquire(&future->ref_count);
}
return future;
}
bool aws_future_impl_is_done(const struct aws_future_impl *future) {
AWS_ASSERT(future);
/* this function is conceptually const, but we need to hold the lock a moment */
struct aws_mutex *mutable_lock = (struct aws_mutex *)&future->lock;
/* BEGIN CRITICAL SECTION */
aws_mutex_lock(mutable_lock);
bool is_done = future->is_done != 0;
aws_mutex_unlock(mutable_lock);
/* END CRITICAL SECTION */
return is_done;
}
int aws_future_impl_get_error(const struct aws_future_impl *future) {
AWS_ASSERT(future != NULL);
/* not bothering with lock, none of this can change after future is done */
AWS_FATAL_ASSERT(future->is_done && "Cannot get error before future is done");
return future->error_code;
}
void *aws_future_impl_get_result_address(const struct aws_future_impl *future) {
AWS_ASSERT(future != NULL);
/* not bothering with lock, none of this can change after future is done */
AWS_FATAL_ASSERT(future->is_done && "Cannot get result before future is done");
AWS_FATAL_ASSERT(!future->error_code && "Cannot get result from future that failed with an error");
AWS_FATAL_ASSERT(future->owns_result && "Result was already moved from future");
const struct aws_future_impl *address_of_memory_after_this_struct = future + 1;
void *result_addr = (void *)address_of_memory_after_this_struct;
return result_addr;
}
void aws_future_impl_get_result_by_move(struct aws_future_impl *future, void *dst_address) {
void *result_addr = aws_future_impl_get_result_address(future);
memcpy(dst_address, result_addr, future->sizeof_result);
memset(result_addr, 0, future->sizeof_result);
future->owns_result = false;
}
/* Data for invoking callback as a task on an event-loop */
struct aws_future_event_loop_callback_job {
struct aws_allocator *alloc;
struct aws_task task;
struct aws_event_loop *event_loop;
aws_future_callback_fn *callback;
void *user_data;
};
static void s_future_impl_event_loop_callback_task(struct aws_task *task, void *arg, enum aws_task_status status) {
(void)task;
(void)status;
struct aws_future_event_loop_callback_job *job = arg;
job->callback(job->user_data);
// TODO: aws_event_loop_release(job->event_loop);
aws_mem_release(job->alloc, job);
}
/* Data for invoking callback as a task on an aws_channel */
struct aws_future_channel_callback_job {
struct aws_allocator *alloc;
struct aws_channel_task task;
struct aws_channel *channel;
aws_future_callback_fn *callback;
void *user_data;
};
static void s_future_impl_channel_callback_task(struct aws_channel_task *task, void *arg, enum aws_task_status status) {
(void)task;
(void)status;
struct aws_future_channel_callback_job *job = arg;
job->callback(job->user_data);
aws_channel_release_hold(job->channel);
aws_mem_release(job->alloc, job);
}
static void s_future_impl_invoke_callback(struct aws_future_callback_data *callback, struct aws_allocator *alloc) {
AWS_ASSERT(callback->fn);
switch (callback->type) {
case AWS_FUTURE_IMMEDIATE_CALLBACK: {
callback->fn(callback->user_data);
} break;
case AWS_FUTURE_EVENT_LOOP_CALLBACK: {
/* Schedule the callback as a task on the event-loop */
struct aws_future_event_loop_callback_job *job =
aws_mem_calloc(alloc, 1, sizeof(struct aws_future_event_loop_callback_job));
job->alloc = alloc;
aws_task_init(&job->task, s_future_impl_event_loop_callback_task, job, "aws_future_event_loop_callback");
job->event_loop = callback->u.event_loop;
job->callback = callback->fn;
job->user_data = callback->user_data;
aws_event_loop_schedule_task_now(callback->u.event_loop, &job->task);
} break;
case AWS_FUTURE_CHANNEL_CALLBACK: {
/* Schedule the callback as a task on the channel */
struct aws_future_channel_callback_job *job =
aws_mem_calloc(alloc, 1, sizeof(struct aws_future_channel_callback_job));
job->alloc = alloc;
aws_channel_task_init(&job->task, s_future_impl_channel_callback_task, job, "aws_future_channel_callback");
job->channel = callback->u.channel;
job->callback = callback->fn;
job->user_data = callback->user_data;
aws_channel_schedule_task_now(callback->u.channel, &job->task);
} break;
}
}
static void s_future_impl_set_done(struct aws_future_impl *future, void *src_address, int error_code) {
bool is_error = error_code != 0;
/* BEGIN CRITICAL SECTION */
aws_mutex_lock(&future->lock);
struct aws_future_callback_data callback = future->callback;
bool first_time = !future->is_done;
if (first_time) {
future->is_done = true;
AWS_ZERO_STRUCT(future->callback);
if (is_error) {
future->error_code = error_code;
} else {
future->owns_result = true;
AWS_FATAL_ASSERT(src_address != NULL);
memcpy(aws_future_impl_get_result_address(future), src_address, future->sizeof_result);
}
aws_condition_variable_notify_all(&future->wait_cvar);
}
aws_mutex_unlock(&future->lock);
/* END CRITICAL SECTION */
if (first_time) {
/* if callback was registered, invoke it now, outside of critical section to avoid deadlock */
if (callback.fn != NULL) {
s_future_impl_invoke_callback(&callback, future->alloc);
}
} else if (!error_code) {
/* future was already done, so just destroy this newer result */
s_future_impl_result_dtor(future, src_address);
}
}
void aws_future_impl_set_error(struct aws_future_impl *future, int error_code) {
AWS_ASSERT(future);
/* handle recoverable usage error */
AWS_ASSERT(error_code != 0);
if (AWS_UNLIKELY(error_code == 0)) {
error_code = AWS_ERROR_UNKNOWN;
}
s_future_impl_set_done(future, NULL /*src_address*/, error_code);
}
void aws_future_impl_set_result_by_move(struct aws_future_impl *future, void *src_address) {
AWS_ASSERT(future);
AWS_ASSERT(src_address);
s_future_impl_set_done(future, src_address, 0 /*error_code*/);
/* the future takes ownership of the result.
* zero out memory at the src_address to reinforce this transfer of ownership. */
memset(src_address, 0, future->sizeof_result);
}
/* Returns true if callback was registered, or false if callback was ignored
* because the the future is already done and invoke_if_already_done==false */
static bool s_future_impl_register_callback(
struct aws_future_impl *future,
struct aws_future_callback_data *callback,
bool invoke_if_already_done) {
/* BEGIN CRITICAL SECTION */
aws_mutex_lock(&future->lock);
AWS_FATAL_ASSERT(future->callback.fn == NULL && "Future done callback must only be set once");
bool already_done = future->is_done != 0;
/* if not done, store callback for later */
if (!already_done) {
future->callback = *callback;
}
aws_mutex_unlock(&future->lock);
/* END CRITICAL SECTION */
/* if already done, invoke callback now */
if (already_done && invoke_if_already_done) {
s_future_impl_invoke_callback(callback, future->alloc);
}
return !already_done || invoke_if_already_done;
}
void aws_future_impl_register_callback(
struct aws_future_impl *future,
aws_future_callback_fn *on_done,
void *user_data) {
AWS_ASSERT(future);
AWS_ASSERT(on_done);
struct aws_future_callback_data callback = {
.fn = on_done,
.user_data = user_data,
.type = AWS_FUTURE_IMMEDIATE_CALLBACK,
};
s_future_impl_register_callback(future, &callback, true /*invoke_if_already_done*/);
}
bool aws_future_impl_register_callback_if_not_done(
struct aws_future_impl *future,
aws_future_callback_fn *on_done,
void *user_data) {
AWS_ASSERT(future);
AWS_ASSERT(on_done);
struct aws_future_callback_data callback = {
.fn = on_done,
.user_data = user_data,
.type = AWS_FUTURE_IMMEDIATE_CALLBACK,
};
return s_future_impl_register_callback(future, &callback, false /*invoke_if_already_done*/);
}
void aws_future_impl_register_event_loop_callback(
struct aws_future_impl *future,
struct aws_event_loop *event_loop,
aws_future_callback_fn *on_done,
void *user_data) {
AWS_ASSERT(future);
AWS_ASSERT(event_loop);
AWS_ASSERT(on_done);
// TODO: aws_event_loop_acquire(event_loop);
struct aws_future_callback_data callback = {
.fn = on_done,
.user_data = user_data,
.type = AWS_FUTURE_EVENT_LOOP_CALLBACK,
.u = {.event_loop = event_loop},
};
s_future_impl_register_callback(future, &callback, true /*invoke_if_already_done*/);
}
void aws_future_impl_register_channel_callback(
struct aws_future_impl *future,
struct aws_channel *channel,
aws_future_callback_fn *on_done,
void *user_data) {
AWS_ASSERT(future);
AWS_ASSERT(channel);
AWS_ASSERT(on_done);
aws_channel_acquire_hold(channel);
struct aws_future_callback_data callback = {
.fn = on_done,
.user_data = user_data,
.type = AWS_FUTURE_CHANNEL_CALLBACK,
.u = {.channel = channel},
};
s_future_impl_register_callback(future, &callback, true /*invoke_if_already_done*/);
}
static bool s_future_impl_is_done_pred(void *user_data) {
struct aws_future_impl *future = user_data;
return future->is_done != 0;
}
bool aws_future_impl_wait(const struct aws_future_impl *future, uint64_t timeout_ns) {
AWS_ASSERT(future);
/* this function is conceptually const, but we need to use synchronization primitives */
struct aws_future_impl *mutable_future = (struct aws_future_impl *)future;
/* BEGIN CRITICAL SECTION */
aws_mutex_lock(&mutable_future->lock);
bool is_done = aws_condition_variable_wait_for_pred(
&mutable_future->wait_cvar,
&mutable_future->lock,
(int64_t)timeout_ns,
s_future_impl_is_done_pred,
mutable_future) == AWS_OP_SUCCESS;
aws_mutex_unlock(&mutable_future->lock);
/* END CRITICAL SECTION */
return is_done;
}
// AWS_FUTURE_T_BY_VALUE_IMPLEMENTATION(aws_future_bool, bool)
struct aws_future_bool *aws_future_bool_new(struct aws_allocator *alloc) {
return (struct aws_future_bool *)aws_future_impl_new_by_value(alloc, sizeof(_Bool));
}
void aws_future_bool_set_result(struct aws_future_bool *future, _Bool result) {
aws_future_impl_set_result_by_move((struct aws_future_impl *)future, &result);
}
_Bool aws_future_bool_get_result(const struct aws_future_bool *future) {
return *(_Bool *)aws_future_impl_get_result_address((const struct aws_future_impl *)future);
}
struct aws_future_bool *aws_future_bool_acquire(struct aws_future_bool *future) {
return (struct aws_future_bool *)aws_future_impl_acquire((struct aws_future_impl *)future);
}
struct aws_future_bool *aws_future_bool_release(struct aws_future_bool *future) {
return (struct aws_future_bool *)aws_future_impl_release((struct aws_future_impl *)future);
}
void aws_future_bool_set_error(struct aws_future_bool *future, int error_code) {
aws_future_impl_set_error((struct aws_future_impl *)future, error_code);
}
_Bool aws_future_bool_is_done(const struct aws_future_bool *future) {
return aws_future_impl_is_done((const struct aws_future_impl *)future);
}
int aws_future_bool_get_error(const struct aws_future_bool *future) {
return aws_future_impl_get_error((const struct aws_future_impl *)future);
}
void aws_future_bool_register_callback(
struct aws_future_bool *future,
aws_future_callback_fn *on_done,
void *user_data) {
aws_future_impl_register_callback((struct aws_future_impl *)future, on_done, user_data);
}
_Bool aws_future_bool_register_callback_if_not_done(
struct aws_future_bool *future,
aws_future_callback_fn *on_done,
void *user_data) {
return aws_future_impl_register_callback_if_not_done((struct aws_future_impl *)future, on_done, user_data);
}
void aws_future_bool_register_event_loop_callback(
struct aws_future_bool *future,
struct aws_event_loop *event_loop,
aws_future_callback_fn *on_done,
void *user_data) {
aws_future_impl_register_event_loop_callback((struct aws_future_impl *)future, event_loop, on_done, user_data);
}
void aws_future_bool_register_channel_callback(
struct aws_future_bool *future,
struct aws_channel *channel,
aws_future_callback_fn *on_done,
void *user_data) {
aws_future_impl_register_channel_callback((struct aws_future_impl *)future, channel, on_done, user_data);
}
_Bool aws_future_bool_wait(struct aws_future_bool *future, uint64_t timeout_ns) {
return aws_future_impl_wait((struct aws_future_impl *)future, timeout_ns);
}
AWS_FUTURE_T_BY_VALUE_IMPLEMENTATION(aws_future_size, size_t)
/**
* aws_future<void>
*/
AWS_FUTURE_T_IMPLEMENTATION_BEGIN(aws_future_void)
struct aws_future_void *aws_future_void_new(struct aws_allocator *alloc) {
/* Use aws_future<bool> under the hood, to avoid edge-cases with 0-sized result */
return (struct aws_future_void *)aws_future_bool_new(alloc);
}
void aws_future_void_set_result(struct aws_future_void *future) {
aws_future_bool_set_result((struct aws_future_bool *)future, false);
}
AWS_FUTURE_T_IMPLEMENTATION_END(aws_future_void)
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