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lib,doc: return boolean from child.send()
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The documentation indicates that child.send() returns a boolean but it
has returned undefinined at since v0.12.0. It now returns a boolean per
the (slightly updated) documentation.

PR-URL: #3516
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
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Trott authored and rvagg committed Oct 29, 2015
1 parent b8cea49 commit f236b3a
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Showing 3 changed files with 15 additions and 5 deletions.
5 changes: 3 additions & 2 deletions doc/api/child_process.markdown
Original file line number Diff line number Diff line change
Expand Up @@ -266,9 +266,10 @@ argument: `null` on success, or an `Error` object on failure.
`child.send()` emits an `'error'` event if no callback was given and the message
cannot be sent, for example because the child process has already exited.

Returns `true` under normal circumstances or `false` when the backlog of
`child.send()` returns `false` if the channel has closed or when the backlog of
unsent messages exceeds a threshold that makes it unwise to send more.
Use the callback mechanism to implement flow control.
Otherwise, it returns `true`. Use the callback mechanism to implement flow
control.

#### Example: sending server object

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6 changes: 3 additions & 3 deletions lib/internal/child_process.js
Original file line number Diff line number Diff line change
Expand Up @@ -504,15 +504,15 @@ function setupChannel(target, channel) {
handle = undefined;
}
if (this.connected) {
this._send(message, handle, false, callback);
return;
return this._send(message, handle, false, callback);
}
const ex = new Error('channel closed');
if (typeof callback === 'function') {
process.nextTick(callback, ex);
} else {
this.emit('error', ex); // FIXME(bnoordhuis) Defer to next tick.
}
return false;
};

target._send = function(message, handle, swallowErrors, callback) {
Expand Down Expand Up @@ -577,7 +577,7 @@ function setupChannel(target, channel) {
handle: null,
message: message,
});
return;
return this._handleQueue.length === 1;
}

var req = new WriteWrap();
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9 changes: 9 additions & 0 deletions test/parallel/test-child-process-send-returns-boolean.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
'use strict';
const common = require('../common');
const assert = require('assert');
const fork = require('child_process').fork;

const n = fork(common.fixturesDir + '/empty.js');

const rv = n.send({ hello: 'world' });
assert.strictEqual(rv, true);

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