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					102 lines
				
				4.0 KiB
			
		
		
			
		
	
	
					102 lines
				
				4.0 KiB
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											3 years ago
										 
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								"use strict";
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								var domain; // The domain module is executed on demand
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								var hasSetImmediate = typeof setImmediate === "function";
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								// Use the fastest means possible to execute a task in its own turn, with
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								// priority over other events including network IO events in Node.js.
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								//
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								// An exception thrown by a task will permanently interrupt the processing of
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								// subsequent tasks. The higher level `asap` function ensures that if an
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								// exception is thrown by a task, that the task queue will continue flushing as
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								// soon as possible, but if you use `rawAsap` directly, you are responsible to
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								// either ensure that no exceptions are thrown from your task, or to manually
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								// call `rawAsap.requestFlush` if an exception is thrown.
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								module.exports = rawAsap;
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								function rawAsap(task) {
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								    if (!queue.length) {
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								        requestFlush();
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								        flushing = true;
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								    }
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								    // Avoids a function call
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								    queue[queue.length] = task;
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								}
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								var queue = [];
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								// Once a flush has been requested, no further calls to `requestFlush` are
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								// necessary until the next `flush` completes.
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								var flushing = false;
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								// The position of the next task to execute in the task queue. This is
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								// preserved between calls to `flush` so that it can be resumed if
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								// a task throws an exception.
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								var index = 0;
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								// If a task schedules additional tasks recursively, the task queue can grow
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								// unbounded. To prevent memory excaustion, the task queue will periodically
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								// truncate already-completed tasks.
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								var capacity = 1024;
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								// The flush function processes all tasks that have been scheduled with
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								// `rawAsap` unless and until one of those tasks throws an exception.
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								// If a task throws an exception, `flush` ensures that its state will remain
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								// consistent and will resume where it left off when called again.
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								// However, `flush` does not make any arrangements to be called again if an
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								// exception is thrown.
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								function flush() {
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								    while (index < queue.length) {
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								        var currentIndex = index;
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								        // Advance the index before calling the task. This ensures that we will
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								        // begin flushing on the next task the task throws an error.
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								        index = index + 1;
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								        queue[currentIndex].call();
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								        // Prevent leaking memory for long chains of recursive calls to `asap`.
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								        // If we call `asap` within tasks scheduled by `asap`, the queue will
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								        // grow, but to avoid an O(n) walk for every task we execute, we don't
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								        // shift tasks off the queue after they have been executed.
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								        // Instead, we periodically shift 1024 tasks off the queue.
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								        if (index > capacity) {
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								            // Manually shift all values starting at the index back to the
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								            // beginning of the queue.
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								            for (var scan = 0, newLength = queue.length - index; scan < newLength; scan++) {
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								                queue[scan] = queue[scan + index];
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								            }
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								            queue.length -= index;
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								            index = 0;
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								        }
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								    }
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								    queue.length = 0;
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								    index = 0;
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								    flushing = false;
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								}
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								rawAsap.requestFlush = requestFlush;
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								function requestFlush() {
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								    // Ensure flushing is not bound to any domain.
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								    // It is not sufficient to exit the domain, because domains exist on a stack.
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								    // To execute code outside of any domain, the following dance is necessary.
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								    var parentDomain = process.domain;
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								    if (parentDomain) {
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								        if (!domain) {
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								            // Lazy execute the domain module.
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								            // Only employed if the user elects to use domains.
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								            domain = require("domain");
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								        }
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								        domain.active = process.domain = null;
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								    }
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								    // `setImmediate` is slower that `process.nextTick`, but `process.nextTick`
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								    // cannot handle recursion.
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								    // `requestFlush` will only be called recursively from `asap.js`, to resume
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								    // flushing after an error is thrown into a domain.
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								    // Conveniently, `setImmediate` was introduced in the same version
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								    // `process.nextTick` started throwing recursion errors.
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								    if (flushing && hasSetImmediate) {
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								        setImmediate(flush);
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								    } else {
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								        process.nextTick(flush);
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								    }
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								    if (parentDomain) {
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								        domain.active = process.domain = parentDomain;
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								    }
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								}
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