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<h1>FileChangeChecker.h</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/*</span>
<a name="l00002"></a>00002 <span class="comment"> * Phusion Passenger - http://www.modrails.com/</span>
<a name="l00003"></a>00003 <span class="comment"> * Copyright (c) 2010 Phusion</span>
<a name="l00004"></a>00004 <span class="comment"> *</span>
<a name="l00005"></a>00005 <span class="comment"> * "Phusion Passenger" is a trademark of Hongli Lai & Ninh Bui.</span>
<a name="l00006"></a>00006 <span class="comment"> *</span>
<a name="l00007"></a>00007 <span class="comment"> * Permission is hereby granted, free of charge, to any person obtaining a copy</span>
<a name="l00008"></a>00008 <span class="comment"> * of this software and associated documentation files (the "Software"), to deal</span>
<a name="l00009"></a>00009 <span class="comment"> * in the Software without restriction, including without limitation the rights</span>
<a name="l00010"></a>00010 <span class="comment"> * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell</span>
<a name="l00011"></a>00011 <span class="comment"> * copies of the Software, and to permit persons to whom the Software is</span>
<a name="l00012"></a>00012 <span class="comment"> * furnished to do so, subject to the following conditions:</span>
<a name="l00013"></a>00013 <span class="comment"> *</span>
<a name="l00014"></a>00014 <span class="comment"> * The above copyright notice and this permission notice shall be included in</span>
<a name="l00015"></a>00015 <span class="comment"> * all copies or substantial portions of the Software.</span>
<a name="l00016"></a>00016 <span class="comment"> *</span>
<a name="l00017"></a>00017 <span class="comment"> * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR</span>
<a name="l00018"></a>00018 <span class="comment"> * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,</span>
<a name="l00019"></a>00019 <span class="comment"> * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE</span>
<a name="l00020"></a>00020 <span class="comment"> * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER</span>
<a name="l00021"></a>00021 <span class="comment"> * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,</span>
<a name="l00022"></a>00022 <span class="comment"> * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN</span>
<a name="l00023"></a>00023 <span class="comment"> * THE SOFTWARE.</span>
<a name="l00024"></a>00024 <span class="comment"> */</span>
<a name="l00025"></a>00025 <span class="preprocessor">#ifndef _PASSENGER_CHANGE_FILE_CHECKER_H_</span>
<a name="l00026"></a>00026 <span class="preprocessor"></span><span class="preprocessor">#define _PASSENGER_CHANGE_FILE_CHECKER_H_</span>
<a name="l00027"></a>00027 <span class="preprocessor"></span>
<a name="l00028"></a>00028 <span class="preprocessor">#include <string></span>
<a name="l00029"></a>00029
<a name="l00030"></a>00030 <span class="preprocessor">#include <boost/thread.hpp></span>
<a name="l00031"></a>00031 <span class="preprocessor">#include <errno.h></span>
<a name="l00032"></a>00032
<a name="l00033"></a>00033 <span class="preprocessor">#include "CachedFileStat.hpp"</span>
<a name="l00034"></a>00034 <span class="preprocessor">#include "SystemTime.h"</span>
<a name="l00035"></a>00035
<a name="l00036"></a>00036 <span class="keyword">namespace </span>Passenger {
<a name="l00037"></a>00037
<a name="l00038"></a>00038 <span class="keyword">using namespace </span>std;
<a name="l00039"></a>00039 <span class="keyword">using namespace </span>oxt;
<a name="l00040"></a>00040 <span class="comment"></span>
<a name="l00041"></a>00041 <span class="comment">/**</span>
<a name="l00042"></a>00042 <span class="comment"> * A utility class for checking for file changes. Example:</span>
<a name="l00043"></a>00043 <span class="comment"> *</span>
<a name="l00044"></a>00044 <span class="comment"> * @code</span>
<a name="l00045"></a>00045 <span class="comment"> * FileChangeChecker checker;</span>
<a name="l00046"></a>00046 <span class="comment"> * checker.changed("foo.txt"); // false</span>
<a name="l00047"></a>00047 <span class="comment"> * writeToFile("foo.txt");</span>
<a name="l00048"></a>00048 <span class="comment"> * checker.changed("foo.txt"); // true</span>
<a name="l00049"></a>00049 <span class="comment"> * checker.changed("foo.txt"); // false</span>
<a name="l00050"></a>00050 <span class="comment"> * @endcode</span>
<a name="l00051"></a>00051 <span class="comment"> *</span>
<a name="l00052"></a>00052 <span class="comment"> * FileChangeChecker uses stat() to retrieve file information. It also</span>
<a name="l00053"></a>00053 <span class="comment"> * supports throttling in order to limit the number of actual stat() calls.</span>
<a name="l00054"></a>00054 <span class="comment"> * This can improve performance on systems where disk I/O is a problem.</span>
<a name="l00055"></a>00055 <span class="comment"> */</span>
<a name="l00056"></a><a class="code" href="classPassenger_1_1FileChangeChecker.html">00056</a> <span class="keyword">class </span><a class="code" href="classPassenger_1_1FileChangeChecker.html" title="A utility class for checking for file changes.">FileChangeChecker</a> {
<a name="l00057"></a>00057 <span class="keyword">private</span>:
<a name="l00058"></a>00058 <span class="keyword">struct </span>Entry {
<a name="l00059"></a>00059 <span class="keywordtype">string</span> filename;
<a name="l00060"></a>00060 time_t lastMtime;
<a name="l00061"></a>00061 time_t lastCtime;
<a name="l00062"></a>00062
<a name="l00063"></a>00063 Entry(<span class="keyword">const</span> <span class="keywordtype">string</span> &filename) {
<a name="l00064"></a>00064 this->filename = filename;
<a name="l00065"></a>00065 this->lastMtime = 0;
<a name="l00066"></a>00066 this->lastCtime = 0;
<a name="l00067"></a>00067 }
<a name="l00068"></a>00068 };
<a name="l00069"></a>00069
<a name="l00070"></a>00070 <span class="keyword">typedef</span> shared_ptr<Entry> EntryPtr;
<a name="l00071"></a>00071 <span class="keyword">typedef</span> list<EntryPtr> EntryList;
<a name="l00072"></a>00072 <span class="keyword">typedef</span> map<string, EntryList::iterator> EntryMap;
<a name="l00073"></a>00073
<a name="l00074"></a>00074 CachedFileStat cstat;
<a name="l00075"></a>00075 <span class="keyword">mutable</span> boost::mutex lock;
<a name="l00076"></a>00076 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> maxSize;
<a name="l00077"></a>00077 EntryList entries;
<a name="l00078"></a>00078 EntryMap fileToEntry;
<a name="l00079"></a>00079
<a name="l00080"></a>00080 <span class="keyword">public</span>:<span class="comment"></span>
<a name="l00081"></a>00081 <span class="comment"> /**</span>
<a name="l00082"></a>00082 <span class="comment"> * Create a FileChangeChecker object.</span>
<a name="l00083"></a>00083 <span class="comment"> *</span>
<a name="l00084"></a>00084 <span class="comment"> * @param maxSize The maximum size of the internal file list. A size of 0 means unlimited.</span>
<a name="l00085"></a>00085 <span class="comment"> */</span>
<a name="l00086"></a><a class="code" href="classPassenger_1_1FileChangeChecker.html#cedaa0a0ed0be509dbbd79abaec25f26">00086</a> <a class="code" href="classPassenger_1_1FileChangeChecker.html#cedaa0a0ed0be509dbbd79abaec25f26" title="Create a FileChangeChecker object.">FileChangeChecker</a>(<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> maxSize = 0)
<a name="l00087"></a>00087 : cstat(maxSize)
<a name="l00088"></a>00088 {
<a name="l00089"></a>00089 this->maxSize = maxSize;
<a name="l00090"></a>00090 }
<a name="l00091"></a>00091 <span class="comment"></span>
<a name="l00092"></a>00092 <span class="comment"> /**</span>
<a name="l00093"></a>00093 <span class="comment"> * Checks whether, since the last call to changed() with this filename,</span>
<a name="l00094"></a>00094 <span class="comment"> * the file's timestamp has changed or whether the file has been created</span>
<a name="l00095"></a>00095 <span class="comment"> * or removed. If the stat() call fails for any other reason (e.g. the</span>
<a name="l00096"></a>00096 <span class="comment"> * directory is not readable) then this method will return false.</span>
<a name="l00097"></a>00097 <span class="comment"> *</span>
<a name="l00098"></a>00098 <span class="comment"> * If this method was called with this filename for the first time, or if</span>
<a name="l00099"></a>00099 <span class="comment"> * information about this file has since been removed from the internal</span>
<a name="l00100"></a>00100 <span class="comment"> * file list, then this method will return whether the file is stat()-able.</span>
<a name="l00101"></a>00101 <span class="comment"> * That is, if the file doesn't exist then it will return false, but if</span>
<a name="l00102"></a>00102 <span class="comment"> * the directory is not readable then it will also return false.</span>
<a name="l00103"></a>00103 <span class="comment"> *</span>
<a name="l00104"></a>00104 <span class="comment"> * @param filename The file to check. Note that two different filename</span>
<a name="l00105"></a>00105 <span class="comment"> * strings are treated as two different files, so you should</span>
<a name="l00106"></a>00106 <span class="comment"> * use absolute filenames if you change working directory</span>
<a name="l00107"></a>00107 <span class="comment"> * often.</span>
<a name="l00108"></a>00108 <span class="comment"> * @param throttleRate When set to a non-zero value, throttling will be</span>
<a name="l00109"></a>00109 <span class="comment"> * enabled. stat() will be called at most once per</span>
<a name="l00110"></a>00110 <span class="comment"> * throttleRate seconds.</span>
<a name="l00111"></a>00111 <span class="comment"> * @throws TimeRetrievalException Something went wrong while retrieving the</span>
<a name="l00112"></a>00112 <span class="comment"> * system time.</span>
<a name="l00113"></a>00113 <span class="comment"> * @throws boost::thread_interrupted</span>
<a name="l00114"></a>00114 <span class="comment"> */</span>
<a name="l00115"></a><a class="code" href="classPassenger_1_1FileChangeChecker.html#52837a877522fb64d70ee1ba965e9135">00115</a> <span class="keywordtype">bool</span> <a class="code" href="classPassenger_1_1FileChangeChecker.html#52837a877522fb64d70ee1ba965e9135" title="Checks whether, since the last call to changed() with this filename, the file&#39;s...">changed</a>(<span class="keyword">const</span> <span class="keywordtype">string</span> &filename, <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> throttleRate = 0) {
<a name="l00116"></a>00116 boost::unique_lock<boost::mutex> l(lock);
<a name="l00117"></a>00117 EntryMap::iterator it(fileToEntry.find(filename));
<a name="l00118"></a>00118 EntryPtr entry;
<a name="l00119"></a>00119 <span class="keyword">struct </span>stat buf;
<a name="l00120"></a>00120 <span class="keywordtype">bool</span> result, newEntry = <span class="keyword">false</span>;
<a name="l00121"></a>00121 <span class="keywordtype">int</span> ret;
<a name="l00122"></a>00122
<a name="l00123"></a>00123 <span class="keywordflow">if</span> (it == fileToEntry.end()) {
<a name="l00124"></a>00124 <span class="comment">// Filename not in file list.</span>
<a name="l00125"></a>00125 <span class="comment">// If file list is full, remove the least recently used</span>
<a name="l00126"></a>00126 <span class="comment">// file list entry.</span>
<a name="l00127"></a>00127 <span class="keywordflow">if</span> (maxSize != 0 && fileToEntry.size() == maxSize) {
<a name="l00128"></a>00128 EntryList::iterator listEnd(entries.end());
<a name="l00129"></a>00129 listEnd--;
<a name="l00130"></a>00130 <span class="keywordtype">string</span> filename((*listEnd)->filename);
<a name="l00131"></a>00131 entries.pop_back();
<a name="l00132"></a>00132 fileToEntry.erase(filename);
<a name="l00133"></a>00133 }
<a name="l00134"></a>00134
<a name="l00135"></a>00135 <span class="comment">// Add to file list as most recently used.</span>
<a name="l00136"></a>00136 entry = EntryPtr(<span class="keyword">new</span> Entry(filename));
<a name="l00137"></a>00137 entries.push_front(entry);
<a name="l00138"></a>00138 fileToEntry[filename] = entries.begin();
<a name="l00139"></a>00139 newEntry = <span class="keyword">true</span>;
<a name="l00140"></a>00140 } <span class="keywordflow">else</span> {
<a name="l00141"></a>00141 <span class="comment">// Filename is in file list.</span>
<a name="l00142"></a>00142 entry = *it->second;
<a name="l00143"></a>00143
<a name="l00144"></a>00144 <span class="comment">// Mark this entry as most recently used.</span>
<a name="l00145"></a>00145 entries.erase(it->second);
<a name="l00146"></a>00146 entries.push_front(entry);
<a name="l00147"></a>00147 fileToEntry[filename] = entries.begin();
<a name="l00148"></a>00148 }
<a name="l00149"></a>00149
<a name="l00150"></a>00150 ret = cstat.stat(filename, &buf, throttleRate);
<a name="l00151"></a>00151 <span class="keywordflow">if</span> (newEntry) {
<a name="l00152"></a>00152 <span class="comment">// The file's information isn't in the file list.</span>
<a name="l00153"></a>00153 <span class="keywordflow">if</span> (ret == -1) {
<a name="l00154"></a>00154 entry->lastMtime = 0;
<a name="l00155"></a>00155 entry->lastCtime = 0;
<a name="l00156"></a>00156 <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00157"></a>00157 } <span class="keywordflow">else</span> {
<a name="l00158"></a>00158 entry->lastMtime = buf.st_mtime;
<a name="l00159"></a>00159 entry->lastCtime = buf.st_ctime;
<a name="l00160"></a>00160 <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00161"></a>00161 }
<a name="l00162"></a>00162 } <span class="keywordflow">else</span> {
<a name="l00163"></a>00163 <span class="comment">// The file's information was already in the file list.</span>
<a name="l00164"></a>00164 <span class="keywordflow">if</span> (ret == -1 && errno == ENOENT) {
<a name="l00165"></a>00165 result = entry->lastMtime != 0 || entry->lastCtime != 0;
<a name="l00166"></a>00166 entry->lastMtime = 0;
<a name="l00167"></a>00167 entry->lastCtime = 0;
<a name="l00168"></a>00168 } <span class="keywordflow">else</span> <span class="keywordflow">if</span> (ret == -1) {
<a name="l00169"></a>00169 result = <span class="keyword">false</span>;
<a name="l00170"></a>00170 } <span class="keywordflow">else</span> {
<a name="l00171"></a>00171 result = entry->lastMtime != buf.st_mtime || entry->lastCtime != buf.st_ctime;
<a name="l00172"></a>00172 entry->lastMtime = buf.st_mtime;
<a name="l00173"></a>00173 entry->lastCtime = buf.st_ctime;
<a name="l00174"></a>00174 }
<a name="l00175"></a>00175 <span class="keywordflow">return</span> result;
<a name="l00176"></a>00176 }
<a name="l00177"></a>00177 }
<a name="l00178"></a>00178 <span class="comment"></span>
<a name="l00179"></a>00179 <span class="comment"> /**</span>
<a name="l00180"></a>00180 <span class="comment"> * Change the maximum size of the internal file list.</span>
<a name="l00181"></a>00181 <span class="comment"> *</span>
<a name="l00182"></a>00182 <span class="comment"> * A size of 0 means unlimited.</span>
<a name="l00183"></a>00183 <span class="comment"> */</span>
<a name="l00184"></a><a class="code" href="classPassenger_1_1FileChangeChecker.html#5055aae067b41fc5fe11747a04b0a1dd">00184</a> <span class="keywordtype">void</span> <a class="code" href="classPassenger_1_1FileChangeChecker.html#5055aae067b41fc5fe11747a04b0a1dd" title="Change the maximum size of the internal file list.">setMaxSize</a>(<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> maxSize) {
<a name="l00185"></a>00185 boost::unique_lock<boost::mutex> l(lock);
<a name="l00186"></a>00186 <span class="keywordflow">if</span> (maxSize != 0) {
<a name="l00187"></a>00187 <span class="keywordtype">int</span> toRemove = fileToEntry.size() - maxSize;
<a name="l00188"></a>00188 <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < toRemove; i++) {
<a name="l00189"></a>00189 <span class="keywordtype">string</span> filename(entries.back()->filename);
<a name="l00190"></a>00190 entries.pop_back();
<a name="l00191"></a>00191 fileToEntry.erase(filename);
<a name="l00192"></a>00192 }
<a name="l00193"></a>00193 }
<a name="l00194"></a>00194 this->maxSize = maxSize;
<a name="l00195"></a>00195 cstat.setMaxSize(maxSize);
<a name="l00196"></a>00196 }
<a name="l00197"></a>00197 <span class="comment"></span>
<a name="l00198"></a>00198 <span class="comment"> /**</span>
<a name="l00199"></a>00199 <span class="comment"> * Returns whether <tt>filename</tt> is in the internal file list.</span>
<a name="l00200"></a>00200 <span class="comment"> */</span>
<a name="l00201"></a><a class="code" href="classPassenger_1_1FileChangeChecker.html#3fb03c747d95f49bddec9e2ca8e8694f">00201</a> <span class="keywordtype">bool</span> <a class="code" href="classPassenger_1_1FileChangeChecker.html#3fb03c747d95f49bddec9e2ca8e8694f" title="Returns whether filename is in the internal file list.">knows</a>(<span class="keyword">const</span> <span class="keywordtype">string</span> &filename)<span class="keyword"> const </span>{
<a name="l00202"></a>00202 boost::unique_lock<boost::mutex> l(lock);
<a name="l00203"></a>00203 <span class="keywordflow">return</span> fileToEntry.find(filename) != fileToEntry.end();
<a name="l00204"></a>00204 }
<a name="l00205"></a>00205 };
<a name="l00206"></a>00206
<a name="l00207"></a>00207 } <span class="comment">// namespace Passenger</span>
<a name="l00208"></a>00208
<a name="l00209"></a>00209 <span class="preprocessor">#endif </span><span class="comment">/* _PASSENGER_CHANGE_FILE_CHECKER_H_ */</span>
</pre></div></div>
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