The Tor Browser / file comparison
comparison: toolkit/components/url-classifier/content/request-backoff.js
toolkit/components/url-classifier/content/request-backoff.js
- branch
- TOR_BUG_9701
- changeset 14
- 925c144e1f1f
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| -1:000000000000 | 0:618b13660492 |
|---|---|
| 1 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 2 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 4 | |
| 5 // This implements logic for stopping requests if the server starts to return | |
| 6 // too many errors. If we get MAX_ERRORS errors in ERROR_PERIOD minutes, we | |
| 7 // back off for TIMEOUT_INCREMENT minutes. If we get another error | |
| 8 // immediately after we restart, we double the timeout and add | |
| 9 // TIMEOUT_INCREMENT minutes, etc. | |
| 10 // | |
| 11 // This is similar to the logic used by the search suggestion service. | |
| 12 | |
| 13 // HTTP responses that count as an error. We also include any 5xx response | |
| 14 // as an error. | |
| 15 const HTTP_FOUND = 302; | |
| 16 const HTTP_SEE_OTHER = 303; | |
| 17 const HTTP_TEMPORARY_REDIRECT = 307; | |
| 18 | |
| 19 /** | |
| 20 * @param maxErrors Number of times to request before backing off. | |
| 21 * @param retryIncrement Time (ms) for each retry before backing off. | |
| 22 * @param maxRequests Number the number of requests needed to trigger backoff | |
| 23 * @param requestPeriod Number time (ms) in which maxRequests have to occur to | |
| 24 * trigger the backoff behavior | |
| 25 * @param timeoutIncrement Number time (ms) the starting timeout period | |
| 26 * we double this time for consecutive errors | |
| 27 * @param maxTimeout Number time (ms) maximum timeout period | |
| 28 */ | |
| 29 function RequestBackoff(maxErrors, retryIncrement, | |
| 30 maxRequests, requestPeriod, | |
| 31 timeoutIncrement, maxTimeout) { | |
| 32 this.MAX_ERRORS_ = maxErrors; | |
| 33 this.RETRY_INCREMENT_ = retryIncrement; | |
| 34 this.MAX_REQUESTS_ = maxRequests; | |
| 35 this.REQUEST_PERIOD_ = requestPeriod; | |
| 36 this.TIMEOUT_INCREMENT_ = timeoutIncrement; | |
| 37 this.MAX_TIMEOUT_ = maxTimeout; | |
| 38 | |
| 39 // Queue of ints keeping the time of all requests | |
| 40 this.requestTimes_ = []; | |
| 41 | |
| 42 this.numErrors_ = 0; | |
| 43 this.errorTimeout_ = 0; | |
| 44 this.nextRequestTime_ = 0; | |
| 45 } | |
| 46 | |
| 47 /** | |
| 48 * Reset the object for reuse. | |
| 49 */ | |
| 50 RequestBackoff.prototype.reset = function() { | |
| 51 this.numErrors_ = 0; | |
| 52 this.errorTimeout_ = 0; | |
| 53 this.nextRequestTime_ = 0; | |
| 54 } | |
| 55 | |
| 56 /** | |
| 57 * Check to see if we can make a request. | |
| 58 */ | |
| 59 RequestBackoff.prototype.canMakeRequest = function() { | |
| 60 var now = Date.now(); | |
| 61 if (now < this.nextRequestTime_) { | |
| 62 return false; | |
| 63 } | |
| 64 | |
| 65 return (this.requestTimes_.length < this.MAX_REQUESTS_ || | |
| 66 (now - this.requestTimes_[0]) > this.REQUEST_PERIOD_); | |
| 67 } | |
| 68 | |
| 69 RequestBackoff.prototype.noteRequest = function() { | |
| 70 var now = Date.now(); | |
| 71 this.requestTimes_.push(now); | |
| 72 | |
| 73 // We only care about keeping track of MAX_REQUESTS | |
| 74 if (this.requestTimes_.length > this.MAX_REQUESTS_) | |
| 75 this.requestTimes_.shift(); | |
| 76 } | |
| 77 | |
| 78 RequestBackoff.prototype.nextRequestDelay = function() { | |
| 79 return Math.max(0, this.nextRequestTime_ - Date.now()); | |
| 80 } | |
| 81 | |
| 82 /** | |
| 83 * Notify this object of the last server response. If it's an error, | |
| 84 */ | |
| 85 RequestBackoff.prototype.noteServerResponse = function(status) { | |
| 86 if (this.isErrorStatus(status)) { | |
| 87 this.numErrors_++; | |
| 88 | |
| 89 if (this.numErrors_ < this.MAX_ERRORS_) | |
| 90 this.errorTimeout_ = this.RETRY_INCREMENT_; | |
| 91 else if (this.numErrors_ == this.MAX_ERRORS_) | |
| 92 this.errorTimeout_ = this.TIMEOUT_INCREMENT_; | |
| 93 else | |
| 94 this.errorTimeout_ *= 2; | |
| 95 | |
| 96 this.errorTimeout_ = Math.min(this.errorTimeout_, this.MAX_TIMEOUT_); | |
| 97 this.nextRequestTime_ = Date.now() + this.errorTimeout_; | |
| 98 } else { | |
| 99 // Reset error timeout, allow requests to go through. | |
| 100 this.reset(); | |
| 101 } | |
| 102 } | |
| 103 | |
| 104 /** | |
| 105 * We consider 302, 303, 307, 4xx, and 5xx http responses to be errors. | |
| 106 * @param status Number http status | |
| 107 * @return Boolean true if we consider this http status an error | |
| 108 */ | |
| 109 RequestBackoff.prototype.isErrorStatus = function(status) { | |
| 110 return ((400 <= status && status <= 599) || | |
| 111 HTTP_FOUND == status || | |
| 112 HTTP_SEE_OTHER == status || | |
| 113 HTTP_TEMPORARY_REDIRECT == status); | |
| 114 } | |
| 115 |
