Constructor
new TaskQueue(maxTokens, refillRate, options)
Properties:
| Name | Type | Description |
|---|---|---|
startingTokens |
number | the number of tokens the bucket starts with (default: |
maxTotalCost |
number | reject a task if total queue cost would pass this limit (default: no limit). |
Creates an instance of TaskQueue.
To allow bursts, set maxTokens to several times the average task cost.
To prevent bursts, set maxTokens to the cost of the largest tasks.
Note that tasks with a cost greater than maxTokens will be rejected.
Parameters:
| Name | Type | Description |
|---|---|---|
maxTokens |
number | the maximum number of tokens in the bucket (burst size). |
refillRate |
number | the number of tokens to be added per second (sustain rate). |
options |
object | optional settings for the new task queue instance. |
Classes
Members
(readonly) length
Get the number of queued tasks which have not yet started.
Methods
_refill()
Refill the token bucket based on the amount of time since the last refill.
_refillAndSpend(cost) → {boolean}
Shorthand for calling _refill() then _spend(cost).
Parameters:
| Name | Type | Description |
|---|---|---|
cost |
number | the number of tokens to try to spend. |
Returns:
true if we had enough tokens; false otherwise.
- Type
- boolean
_runTasks()
Loop until the task queue is empty, running each task and spending tokens to do so. Any time the bucket can't afford the next task, delay asynchronously until it can.
_spend(cost) → {boolean}
If we can "afford" the given cost, subtract that many tokens and return true. Otherwise, return false.
Parameters:
| Name | Type | Description |
|---|---|---|
cost |
number | the number of tokens to try to spend. |
Returns:
true if we had enough tokens; false otherwise.
- Type
- boolean
cancel(taskPromise) → {boolean}
Cancel one pending task, rejecting its promise.
Parameters:
| Name | Type | Description |
|---|---|---|
taskPromise |
Promise | the promise returned by |
Returns:
- true if the task was found, or false otherwise.
- Type
- boolean
cancelAll()
Cancel all pending tasks, rejecting all their promises.
do(task, costopt) → {Promise}
Wait until the token bucket is full enough, then run the provided task.
Parameters:
| Name | Type | Attributes | Default | Description |
|---|---|---|---|---|
task |
function | the task to run. |
||
cost |
number |
<optional> |
1
|
the number of tokens this task consumes from the bucket. |
Returns:
- a promise for the task's return value.
- Type
- Promise