diff options
Diffstat (limited to 'background_scripts/search_engines.coffee')
| -rw-r--r-- | background_scripts/search_engines.coffee | 85 |
1 files changed, 37 insertions, 48 deletions
diff --git a/background_scripts/search_engines.coffee b/background_scripts/search_engines.coffee index abf8c86e..3ddbe742 100644 --- a/background_scripts/search_engines.coffee +++ b/background_scripts/search_engines.coffee @@ -114,38 +114,16 @@ completionEngines = [ ] SearchEngines = - cancel: (searchUrl, callback = null) -> - @requests[searchUrl]?.abort() - delete @requests[searchUrl] - callback? null - - # Perform an HTTP GET. get: (searchUrl, url, callback) -> - @requests ?= {} # Maps a searchUrl to any outstanding HTTP request for that search engine. - @cancel searchUrl - - # We cache the results of the most-recent 100 successfully XMLHttpRequests with a ten-second (ie. very - # short) expiry. - @requestCache ?= new SimpleCache 10 * 1000, 100 - - if @requestCache.has url - callback @requestCache.get url - return - - @requests[searchUrl] = xhr = new XMLHttpRequest() + xhr = new XMLHttpRequest() xhr.open "GET", url, true - xhr.timeout = 750 - xhr.ontimeout = => @cancel searchUrl, callback - xhr.onerror = => @cancel searchUrl, callback + xhr.timeout = 1000 + xhr.ontimeout = xhr.onerror = -> callback null xhr.send() - xhr.onreadystatechange = => + xhr.onreadystatechange = -> if xhr.readyState == 4 - @requests[searchUrl] = null - if xhr.status == 200 - callback @requestCache.set url, xhr - else - callback null + callback(if xhr.status == 200 then xhr else null) # Look up the search-completion engine for this searchUrl. Because of DummySearchEngine, above, we know # there will always be a match. Imagining that there may be many completion engines, and knowing that this @@ -176,7 +154,7 @@ SearchEngines = return callback [] if Utils.hasJavascriptPrefix queryTerms[0] # Cache completions. However, completions depend upon both the searchUrl and the query terms. So we need - # to generate a key. We mix in some nonsense generated by pwgen. A key clash is possible, but vanishingly + # to generate a key. We mix in some junk generated by pwgen. A key clash is possible, but vanishingly # unlikely. junk = "//Zi?ei5;o//" completionCacheKey = searchUrl + junk + queryTerms.join junk @@ -184,26 +162,37 @@ SearchEngines = if @completionCache.has completionCacheKey return callback @completionCache.get completionCacheKey - engine = @lookupEngine searchUrl - url = engine.getUrl queryTerms - query = queryTerms.join(" ").toLowerCase() - @get searchUrl, url, (xhr = null) => - # Parsing the response may fail if we receive an unexpected or an unexpectedly-formatted response. In - # all cases, we fall back to the catch clause, below. - try - suggestions = engine.parse xhr - # Make sure we really do have an iterable of strings. - suggestions = (suggestion for suggestion in suggestions when "string" == typeof suggestion) - # Filter out the query itself. It's not adding anything. - suggestions = (suggestion for suggestion in suggestions when suggestion.toLowerCase() != query) - # We keep at most three suggestions, the top three. - callback @completionCache.set completionCacheKey, suggestions[...3] - catch - callback @completionCache.set completionCacheKey, callback [] - # We cache failures, but remove them after just ten minutes. This (it is hoped) avoids repeated - # XMLHttpRequest failures over a short period of time. - removeCompletionCacheKey = => @completionCache.set completionCacheKey, null - setTimeout removeCompletionCacheKey, 10 * 60 * 1000 # Ten minutes. + fetchSuggestions = (callback) => + engine = @lookupEngine searchUrl + url = engine.getUrl queryTerms + query = queryTerms.join(" ").toLowerCase() + @get searchUrl, url, (xhr = null) => + # Parsing the response may fail if we receive an unexpected or an unexpectedly-formatted response. In + # all cases, we fall back to the catch clause, below. + try + suggestions = engine.parse xhr + # Make sure we really do have an iterable of strings. + suggestions = (suggestion for suggestion in suggestions when "string" == typeof suggestion) + # Filter out the query itself. It's not adding anything. + suggestions = (suggestion for suggestion in suggestions when suggestion.toLowerCase() != query) + catch + suggestions = [] + # We cache failures, but remove them after just ten minutes. This (it is hoped) avoids repeated + # XMLHttpRequest failures over a short period of time. + removeCompletionCacheKey = => @completionCache.set completionCacheKey, null + setTimeout removeCompletionCacheKey, 10 * 60 * 1000 # Ten minutes. + + callback suggestions + + # Don't allow duplicate identical active requests. This can happen, for example, when the user enters or + # removes a space, or when they enter a character and immediately delete it. + @inTransit ?= {} + unless @inTransit[completionCacheKey]?.push callback + queue = @inTransit[completionCacheKey] = [] + fetchSuggestions (suggestions) => + callback @completionCache.set completionCacheKey, suggestions + delete @inTransit[completionCacheKey] + callback suggestions for callback in queue root = exports ? window root.SearchEngines = SearchEngines |