#include <userver/dist_lock/dist_locked_task.hpp>
A task that tries to acquire a distributed lock and runs user callback once while the lock is held.
When dist lock starts, the lock worker tries to take a lock in the loop. If succeeded, a task is launched that executes the user code. In the background, dist lock tries to extend the lock. In case of loss of the lock, the user task is canceled.
Definition at line 48 of file dist_locked_task.hpp.
Public Types | |
using | WorkerFunc = std::function<void()> |
Public Types inherited from engine::TaskBase | |
enum class | Importance { kNormal , kCritical } |
Task importance. More... | |
enum class | State { kInvalid , kNew , kQueued , kRunning , kSuspended , kCancelled , kCompleted } |
Task state. More... | |
enum class | WaitMode { kSingleWaiter , kMultipleWaiters } |
Task wait mode. More... | |
Public Member Functions | |
DistLockedTask ()=default | |
DistLockedTask (DistLockedTask &&)=delete | |
DistLockedTask & | operator= (DistLockedTask &&)=delete |
DistLockedTask (const DistLockedTask &)=delete | |
DistLockedTask & | operator= (const DistLockedTask &&)=delete |
DistLockedTask (std::string name, WorkerFunc worker_func, std::shared_ptr< DistLockStrategyBase > strategy, const DistLockSettings &settings={}, DistLockWaitingMode mode=DistLockWaitingMode::kWait, DistLockRetryMode retry_mode=DistLockRetryMode::kRetry) | |
DistLockedTask (engine::TaskProcessor &task_processor, std::string name, WorkerFunc worker_func, std::shared_ptr< DistLockStrategyBase > strategy, const DistLockSettings &settings={}, DistLockWaitingMode mode=DistLockWaitingMode::kWait, DistLockRetryMode retry_mode=DistLockRetryMode::kRetry) | |
Creates a DistLockedTask to be run in a specific engine::TaskProcessor. | |
std::optional< std::chrono::steady_clock::duration > | GetLockedDuration () const |
void | Get () noexcept(false) |
Public Member Functions inherited from engine::TaskBase | |
bool | IsValid () const |
Checks whether this object owns an actual task (not State::kInvalid ) | |
State | GetState () const |
Gets the task State. | |
bool | IsFinished () const |
Returns whether the task finished execution. | |
void | Wait () const noexcept(false) |
Suspends execution until the task finishes or caller is cancelled. Can be called from coroutine context only. For non-coroutine context use BlockingWait(). | |
template<typename Rep , typename Period > | |
void | WaitFor (const std::chrono::duration< Rep, Period > &) const noexcept(false) |
Suspends execution until the task finishes or after the specified timeout or until caller is cancelled. | |
template<typename Clock , typename Duration > | |
void | WaitUntil (const std::chrono::time_point< Clock, Duration > &) const noexcept(false) |
Suspends execution until the task finishes or until the specified time point is reached or until caller is cancelled. | |
void | WaitUntil (Deadline) const |
Suspends execution until the task finishes or until the specified deadline is reached or until caller is cancelled. | |
void | RequestCancel () |
Queues task cancellation request. | |
void | SyncCancel () noexcept |
Cancels the task and suspends execution until it is finished. Can be called from coroutine context only. For non-coroutine context use RequestCancel() + BlockingWait(). | |
TaskCancellationReason | CancellationReason () const |
Gets task cancellation reason. | |
void | BlockingWait () const |
Additional Inherited Members | |
Static Public Member Functions inherited from engine::TaskBase | |
static const std::string & | GetStateName (State state) |
using dist_lock::DistLockedTask::WorkerFunc = std::function<void()> |
Definition at line 50 of file dist_locked_task.hpp.
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default |
Default constructor. Creates an invalid task.
dist_lock::DistLockedTask::DistLockedTask | ( | std::string | name, |
WorkerFunc | worker_func, | ||
std::shared_ptr< DistLockStrategyBase > | strategy, | ||
const DistLockSettings & | settings = {}, | ||
DistLockWaitingMode | mode = DistLockWaitingMode::kWait, | ||
DistLockRetryMode | retry_mode = DistLockRetryMode::kRetry ) |
Creates a DistLockedTask.
name | name of the task |
worker_func | a callback that is started once we've acquired the lock and is cancelled when the lock is lost. |
settings | distributed lock settings |
strategy | distributed locking strategy |
mode | distributed lock waiting mode |
worker_func
must honour task cancellation and stop ASAP when it is cancelled, otherwise brain split is possible (IOW, two different users do work assuming both of them hold the lock, which is not true). std::optional< std::chrono::steady_clock::duration > dist_lock::DistLockedTask::GetLockedDuration | ( | ) | const |
Returns for how long the lock is held (if held at all). Returned value may be less than the real duration.