Skip to content

Commit

Permalink
async_hooks: rename currentId and triggerId
Browse files Browse the repository at this point in the history 
currentId is renamed to executionAsyncId
triggerId is renamed to triggerAsyncId
AsyncResource.triggerId is renamed to AsyncResource.triggerAsyncId
AsyncHooksGetCurrentId is renamed to AsyncHooksGetExecutionAsyncId
AsyncHooksGetTriggerId is renamed to AsyncHooksGetTriggerAsyncId

PR-URL: #13490
Reviewed-By: Refael Ackermann <[email protected]>
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Trevor Norris <[email protected]>
  • Loading branch information
@AndreasMadsen @addaleax
AndreasMadsen authored and addaleax committed Jul 11, 2017
1 parent 6512fd7 commit 3bb4ec8
Show file tree
Hide file tree
Showing 65 changed files with 395 additions and 307 deletions.
105 changes: 53 additions & 52 deletions doc/api/async_hooks.md
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,11 +29,11 @@ Following is a simple overview of the public API.
const async_hooks = require('async_hooks');

// Return the ID of the current execution context.
const cid = async_hooks.currentId();
const eid = async_hooks.executionAsyncId();

// Return the ID of the handle responsible for triggering the callback of the
// current execution scope to call.
const tid = async_hooks.triggerId();
const tid = async_hooks.triggerAsyncId();

// Create a new AsyncHook instance. All of these callbacks are optional.
const asyncHook = async_hooks.createHook({ init, before, after, destroy });
Expand All @@ -53,7 +53,7 @@ asyncHook.disable();
// init is called during object construction. The resource may not have
// completed construction when this callback runs, therefore all fields of the
// resource referenced by "asyncId" may not have been populated.
function init(asyncId, type, triggerId, resource) { }
function init(asyncId, type, triggerAsyncId, resource) { }

// before is called just before the resource's callback is called. It can be
// called 0-N times for handles (e.g. TCPWrap), and will be called exactly 1
Expand Down Expand Up @@ -163,11 +163,11 @@ Key events in the lifetime of asynchronous events have been categorized into
four areas: instantiation, before/after the callback is called, and when the
instance is destructed.

##### `init(asyncId, type, triggerId, resource)`
##### `init(asyncId, type, triggerAsyncId, resource)`

* `asyncId` {number} a unique ID for the async resource
* `type` {string} the type of the async resource
* `triggerId` {number} the unique ID of the async resource in whose
* `triggerAsyncId` {number} the unique ID of the async resource in whose
execution context this async resource was created
* `resource` {Object} reference to the resource representing the async operation,
needs to be released during _destroy_
Expand Down Expand Up @@ -214,20 +214,20 @@ when listening to the hooks.

###### `triggerId`

`triggerId` is the `asyncId` of the resource that caused (or "triggered") the
`triggerAsyncId` is the `asyncId` of the resource that caused (or "triggered") the
new resource to initialize and that caused `init` to call. This is different
from `async_hooks.currentId()` that only shows *when* a resource was created,
while `triggerId` shows *why* a resource was created.
from `async_hooks.executionAsyncId()` that only shows *when* a resource was
created, while `triggerAsyncId` shows *why* a resource was created.


The following is a simple demonstration of `triggerId`:
The following is a simple demonstration of `triggerAsyncId`:

```js
async_hooks.createHook({
init(asyncId, type, triggerId) {
const cId = async_hooks.currentId();
init(asyncId, type, triggerAsyncId) {
const eid = async_hooks.executionAsyncId();
fs.writeSync(
1, `${type}(${asyncId}): trigger: ${triggerId} scope: ${cId}\n`);
1, `${type}(${asyncId}): trigger: ${triggerAsyncId} execution: ${eid}\n`);
}
}).enable();

Expand All @@ -237,18 +237,18 @@ require('net').createServer((conn) => {}).listen(8080);
Output when hitting the server with `nc localhost 8080`:

```
TCPWRAP(2): trigger: 1 scope: 1
TCPWRAP(4): trigger: 2 scope: 0
TCPWRAP(2): trigger: 1 execution: 1
TCPWRAP(4): trigger: 2 execution: 0
```

The first `TCPWRAP` is the server which receives the connections.

The second `TCPWRAP` is the new connection from the client. When a new
connection is made the `TCPWrap` instance is immediately constructed. This
happens outside of any JavaScript stack (side note: a `currentId()` of `0`
happens outside of any JavaScript stack (side note: a `executionAsyncId()` of `0`
means it's being executed from C++, with no JavaScript stack above it).
With only that information it would be impossible to link resources together in
terms of what caused them to be created, so `triggerId` is given the task of
terms of what caused them to be created, so `triggerAsyncId` is given the task of
propagating what resource is responsible for the new resource's existence.

###### `resource`
Expand Down Expand Up @@ -280,12 +280,13 @@ elaborate to make calling context easier to see.
```js
let indent = 0;
async_hooks.createHook({
init(asyncId, type, triggerId) {
const cId = async_hooks.currentId();
init(asyncId, type, triggerAsyncId) {
const eid = async_hooks.executionAsyncId();
const indentStr = ' '.repeat(indent);
fs.writeSync(
1,
`${indentStr}${type}(${asyncId}): trigger: ${triggerId} scope: ${cId}\n`);
`${indentStr}${type}(${asyncId}):` +
` trigger: ${triggerAsyncId} execution: ${eid}\n`);
},
before(asyncId) {
const indentStr = ' '.repeat(indent);
Expand All @@ -306,28 +307,28 @@ async_hooks.createHook({
require('net').createServer(() => {}).listen(8080, () => {
// Let's wait 10ms before logging the server started.
setTimeout(() => {
console.log('>>>', async_hooks.currentId());
console.log('>>>', async_hooks.executionAsyncId());
}, 10);
});
```

Output from only starting the server:

```
TCPWRAP(2): trigger: 1 scope: 1
TickObject(3): trigger: 2 scope: 1
TCPWRAP(2): trigger: 1 execution: 1
TickObject(3): trigger: 2 execution: 1
before: 3
Timeout(4): trigger: 3 scope: 3
TIMERWRAP(5): trigger: 3 scope: 3
Timeout(4): trigger: 3 execution: 3
TIMERWRAP(5): trigger: 3 execution: 3
after: 3
destroy: 3
before: 5
before: 4
TTYWRAP(6): trigger: 4 scope: 4
SIGNALWRAP(7): trigger: 4 scope: 4
TTYWRAP(8): trigger: 4 scope: 4
TTYWRAP(6): trigger: 4 execution: 4
SIGNALWRAP(7): trigger: 4 execution: 4
TTYWRAP(8): trigger: 4 execution: 4
>>> 4
TickObject(9): trigger: 4 scope: 4
TickObject(9): trigger: 4 execution: 4
after: 4
after: 5
before: 9
Expand All @@ -337,11 +338,11 @@ destroy: 9
destroy: 5
```

*Note*: As illustrated in the example, `currentId()` and `scope` each specify
the value of the current execution context; which is delineated by calls to
`before` and `after`.
*Note*: As illustrated in the example, `executionAsyncId()` and `execution`
each specify the value of the current execution context; which is delineated by
calls to `before` and `after`.

Only using `scope` to graph resource allocation results in the following:
Only using `execution` to graph resource allocation results in the following:

```
TTYWRAP(6) -> Timeout(4) -> TIMERWRAP(5) -> TickObject(3) -> root(1)
Expand All @@ -353,7 +354,7 @@ hostname is actually synchronous, but to maintain a completely asynchronous API
the user's callback is placed in a `process.nextTick()`.

The graph only shows *when* a resource was created, not *why*, so to track
the *why* use `triggerId`.
the *why* use `triggerAsyncId`.


##### `before(asyncId)`
Expand Down Expand Up @@ -396,39 +397,39 @@ the `resource` object passed to `init` it's possible that `destroy` is
never called, causing a memory leak in the application. Of course if
the resource doesn't depend on GC then this isn't an issue.

#### `async_hooks.currentId()`
#### `async_hooks.executionAsyncId()`

* Returns {number} the `asyncId` of the current execution context. Useful to track
when something calls.

For example:

```js
console.log(async_hooks.currentId()); // 1 - bootstrap
console.log(async_hooks.executionAsyncId()); // 1 - bootstrap
fs.open(path, 'r', (err, fd) => {
console.log(async_hooks.currentId()); // 6 - open()
console.log(async_hooks.executionAsyncId()); // 6 - open()
});
```

It is important to note that the ID returned fom `currentId()` is related to
execution timing, not causality (which is covered by `triggerId()`). For
It is important to note that the ID returned fom `executionAsyncId()` is related
to execution timing, not causality (which is covered by `triggerAsyncId()`). For
example:

```js
const server = net.createServer(function onConnection(conn) {
// Returns the ID of the server, not of the new connection, because the
// onConnection callback runs in the execution scope of the server's
// MakeCallback().
async_hooks.currentId();
async_hooks.executionAsyncId();

}).listen(port, function onListening() {
// Returns the ID of a TickObject (i.e. process.nextTick()) because all
// callbacks passed to .listen() are wrapped in a nextTick().
async_hooks.currentId();
async_hooks.executionAsyncId();
});
```

#### `async_hooks.triggerId()`
#### `async_hooks.triggerAsyncId()`

* Returns {number} the ID of the resource responsible for calling the callback
that is currently being executed.
Expand All @@ -438,15 +439,15 @@ For example:
```js
const server = net.createServer((conn) => {
// The resource that caused (or triggered) this callback to be called
// was that of the new connection. Thus the return value of triggerId()
// was that of the new connection. Thus the return value of triggerAsyncId()
// is the asyncId of "conn".
async_hooks.triggerId();
async_hooks.triggerAsyncId();

}).listen(port, () => {
// Even though all callbacks passed to .listen() are wrapped in a nextTick()
// the callback itself exists because the call to the server's .listen()
// was made. So the return value would be the ID of the server.
async_hooks.triggerId();
async_hooks.triggerAsyncId();
});
```

Expand Down Expand Up @@ -475,9 +476,9 @@ The following is an overview of the `AsyncResource` API.
const { AsyncResource } = require('async_hooks');

// AsyncResource() is meant to be extended. Instantiating a
// new AsyncResource() also triggers init. If triggerId is omitted then
// async_hook.currentId() is used.
const asyncResource = new AsyncResource(type, triggerId);
// new AsyncResource() also triggers init. If triggerAsyncId is omitted then
// async_hook.executionAsyncId() is used.
const asyncResource = new AsyncResource(type, triggerAsyncId);

// Call AsyncHooks before callbacks.
asyncResource.emitBefore();
Expand All @@ -492,14 +493,14 @@ asyncResource.emitDestroy();
asyncResource.asyncId();

// Return the trigger ID for the AsyncResource instance.
asyncResource.triggerId();
asyncResource.triggerAsyncId();
```

#### `AsyncResource(type[, triggerId])`
#### `AsyncResource(type[, triggerAsyncId])`

* arguments
* `type` {string} the type of ascyc event
* `triggerId` {number} the ID of the execution context that created this async
* `triggerAsyncId` {number} the ID of the execution context that created this async
event

Example usage:
Expand Down Expand Up @@ -558,9 +559,9 @@ never be called.

* Returns {number} the unique `asyncId` assigned to the resource.

#### `asyncResource.triggerId()`
#### `asyncResource.triggerAsyncId()`

* Returns {number} the same `triggerId` that is passed to the `AsyncResource`
* Returns {number} the same `triggerAsyncId` that is passed to the `AsyncResource`
constructor.

[`Hook Callbacks`]: #hook-callbacks
30 changes: 30 additions & 0 deletions doc/api/deprecations.md
View file
Original file line number Diff line number Diff line change
Expand Up @@ -600,6 +600,36 @@ The DebugContext will be removed in V8 soon and will not be available in Node

*Note*: DebugContext was an experimental API.

<a id="DEP0070"></a>
### DEP0070: async_hooks.currentId()

Type: Runtime

`async_hooks.currentId()` was renamed to `async_hooks.executionAsyncId()` for
clarity.

*Note*: change was made while `async_hooks` was an experimental API.

<a id="DEP0071"></a>
### DEP0071: async_hooks.triggerId()

Type: Runtime

`async_hooks.triggerId()` was renamed to `async_hooks.triggerAsyncId()` for
clarity.

*Note*: change was made while `async_hooks` was an experimental API.

<a id="DEP0072"></a>
### DEP0072: async_hooks.AsyncResource.triggerId()

Type: Runtime

`async_hooks.AsyncResource.triggerId()` was renamed to
`async_hooks.AsyncResource.triggerAsyncId()` for clarity.

*Note*: change was made while `async_hooks` was an experimental API.

[`Buffer.allocUnsafeSlow(size)`]: buffer.html#buffer_class_method_buffer_allocunsafeslow_size
[`Buffer.from(array)`]: buffer.html#buffer_class_method_buffer_from_array
[`Buffer.from(buffer)`]: buffer.html#buffer_class_method_buffer_from_buffer
Expand Down
Loading

0 comments on commit 3bb4ec8

Please sign in to comment.