README
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Sequent
Go library for sequential background processing.
This library depends on the watchdog and backoff libraries, which will reinvoke methods until success based on a given backoff strategy.
Example
First, create an Executor. The alternate constructor, NewExecutorWithBackoff
creates an executor instance with a non-default backoff strategy. The default
strategy is an exponential strategy with some random jitter. Before scheduling
a task, the executor must be started, which will begin processing the work queue
in a goroutine.
executor := NewExecutor()
executor.Start()
Tasks can then be scheduled via the Schedule method. A task should be a method
that returns true on success and false on failure. Each task is executed in the
order that it was scheduled; task n will not begin until task n-1 has already
successfully finished.
executor.Signal(func() bool {
if ok := /* re-execute failed redis command */; ok {
return true
}
fmt.Printf("Redis is still down.\n")
return false
})
The user is also responsible for stopping the executor, which can be done by the
following two methods. Use the Stop method if the executor should abandon the
current task and ignore any queued tasks which have not yet been invoked. Use the
Flush method instead to wait for all queued tasks to finish processing.
executor.Stop() // immediate shutdown
executor.Flush() // graceful shutdown
License
Copyright (c) 2017 Eric Fritz
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Documentation
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Index ¶
Constants ¶
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Variables ¶
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Functions ¶
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Types ¶
type ConfigFunc ¶
type ConfigFunc func(*executor)
ConfigFunc is a function used to initialize a new executor.
func WithBackoff ¶
func WithBackoff(backoff backoff.Backoff) ConfigFunc
WithBackoff sets the backoff strategy to use (default is an exponential strategy with a maximum of 30 seconds).
type Executor ¶
type Executor interface {
// Start will begin processing scheduled tasks. This method must not block.
Start()
// Schedule will put a task at the end of the processing queue. This method
// will block if Start has not been called, and must not be called after a
// call to Stop or Flush.
Schedule(task Task)
// Stop immediately drops the current task and exit the processing loop. This
// method does not attempt to interrupt the currently running task, but its
// return value will be ignored by the calling function.
Stop()
// Flush blocks until the queue has been completely processed. This method is
// the graceful version of Stop.
Flush()
}
Executor abstracts a sequence of tasks which are processed, in order, in a background goroutine. New tasks can be scheduled in a non-blocking manner.
func NewExecutor ¶
func NewExecutor(configs ...ConfigFunc) Executor
NewExecutor creates a new Executor.
Source Files