xpcom/base/nsConsoleService.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /* ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
   9  *
  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is mozilla.org code.
  16  *
  17  * The Initial Developer of the Original Code is
  18  * Netscape Communications Corporation.
  19  * Portions created by the Initial Developer are Copyright (C) 1998
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *   Simon Bünzli <zeniko@gmail.com>
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * either of the GNU General Public License Version 2 or later (the "GPL"),
  27  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  28  * in which case the provisions of the GPL or the LGPL are applicable instead
  29  * of those above. If you wish to allow use of your version of this file only
  30  * under the terms of either the GPL or the LGPL, and not to allow others to
  31  * use your version of this file under the terms of the MPL, indicate your
  32  * decision by deleting the provisions above and replace them with the notice
  33  * and other provisions required by the GPL or the LGPL. If you do not delete
  34  * the provisions above, a recipient may use your version of this file under
  35  * the terms of any one of the MPL, the GPL or the LGPL.
  36  *
  37  * ***** END LICENSE BLOCK ***** */
  38
  39 /*
  40  * Maintains a circular buffer of recent messages, and notifies
  41  * listeners when new messages are logged.
  42  */
  43
  44 /* Threadsafe. */
  45
  46 #include "nsMemory.h"
  47 #include "nsIServiceManager.h"
  48 #include "nsIProxyObjectManager.h"
  49 #include "nsCOMArray.h"
  50 #include "nsThreadUtils.h"
  51
  52 #include "nsConsoleService.h"
  53 #include "nsConsoleMessage.h"
  54 #include "nsIClassInfoImpl.h"
  55
  56 NS_IMPL_THREADSAFE_ADDREF(nsConsoleService)
  57 NS_IMPL_THREADSAFE_RELEASE(nsConsoleService)
  58 NS_IMPL_CLASSINFO(nsConsoleService, NULL, nsIClassInfo::THREADSAFE | nsIClassInfo::SINGLETON, NS_CONSOLESERVICE_CID)
  59 NS_IMPL_QUERY_INTERFACE1_CI(nsConsoleService, nsIConsoleService)
  60 NS_IMPL_CI_INTERFACE_GETTER1(nsConsoleService, nsIConsoleService)
  61
  62 nsConsoleService::nsConsoleService()
  63     : mMessages(nsnull), mCurrent(0), mFull(PR_FALSE), mListening(PR_FALSE), mLock(nsnull)
  64 {
  65     // XXX grab this from a pref!
  66     // hm, but worry about circularity, bc we want to be able to report
  67     // prefs errs...
  68     mBufferSize = 250;
  69 }
  70
  71 nsConsoleService::~nsConsoleService()
  72 {
  73     PRUint32 i = 0;
  74     while (i < mBufferSize && mMessages[i] != nsnull) {
  75         NS_RELEASE(mMessages[i]);
  76         i++;
  77     }
  78
  79 #ifdef DEBUG_mccabe
  80     if (mListeners.Count() != 0) {
  81         fprintf(stderr,
  82             "WARNING - %d console error listeners still registered!\n"
  83             "More calls to nsIConsoleService::UnregisterListener needed.\n",
  84             mListeners.Count());
  85     }
  86
  87 #endif
  88
  89     if (mMessages)
  90         nsMemory::Free(mMessages);
  91     if (mLock)
  92         PR_DestroyLock(mLock);
  93 }
  94
  95 nsresult
  96 nsConsoleService::Init()
  97 {
  98     mMessages = (nsIConsoleMessage **)
  99         nsMemory::Alloc(mBufferSize * sizeof(nsIConsoleMessage *));
 100     if (!mMessages)
 101         return NS_ERROR_OUT_OF_MEMORY;
 102
 103     // Array elements should be 0 initially for circular buffer algorithm.
 104     memset(mMessages, 0, mBufferSize * sizeof(nsIConsoleMessage *));
 105
 106     mLock = PR_NewLock();
 107     if (!mLock)
 108         return NS_ERROR_OUT_OF_MEMORY;
 109
 110     return NS_OK;
 111 }
 112
 113 static PRBool snapshot_enum_func(nsHashKey *key, void *data, void* closure)
 114 {
 115     nsCOMArray<nsIConsoleListener> *array =
 116       reinterpret_cast<nsCOMArray<nsIConsoleListener> *>(closure);
 117
 118     // Copy each element into the temporary nsCOMArray...
 119     array->AppendObject((nsIConsoleListener*)data);
 120     return PR_TRUE;
 121 }
 122
 123 // nsIConsoleService methods
 124 NS_IMETHODIMP
 125 nsConsoleService::LogMessage(nsIConsoleMessage *message)
 126 {
 127     if (message == nsnull)
 128         return NS_ERROR_INVALID_ARG;
 129
 130     nsCOMArray<nsIConsoleListener> listenersSnapshot;
 131     nsIConsoleMessage *retiredMessage;
 132
 133     NS_ADDREF(message); // early, in case it's same as replaced below.
 134
 135     /*
 136      * Lock while updating buffer, and while taking snapshot of
 137      * listeners array.
 138      */
 139     {
 140         nsAutoLock lock(mLock);
 141
 142         /*
 143          * If there's already a message in the slot we're about to replace,
 144          * we've wrapped around, and we need to release the old message.  We
 145          * save a pointer to it, so we can release below outside the lock.
 146          */
 147         retiredMessage = mMessages[mCurrent];
 148
 149         mMessages[mCurrent++] = message;
 150         if (mCurrent == mBufferSize) {
 151             mCurrent = 0; // wrap around.
 152             mFull = PR_TRUE;
 153         }
 154
 155         /*
 156          * Copy the listeners into the snapshot array - in case a listener
 157          * is removed during an Observe(...) notification...
 158          */
 159         mListeners.Enumerate(snapshot_enum_func, &listenersSnapshot);
 160     }
 161     if (retiredMessage != nsnull)
 162         NS_RELEASE(retiredMessage);
 163
 164     /*
 165      * Iterate through any registered listeners and tell them about
 166      * the message.  We use the mListening flag to guard against
 167      * recursive message logs.  This could sometimes result in
 168      * listeners being skipped because of activity on other threads,
 169      * when we only care about the recursive case.
 170      */
 171     nsCOMPtr<nsIConsoleListener> listener;
 172     PRInt32 snapshotCount = listenersSnapshot.Count();
 173
 174     {
 175         nsAutoLock lock(mLock);
 176         if (mListening)
 177             return NS_OK;
 178         mListening = PR_TRUE;
 179     }
 180
 181     for (PRInt32 i = 0; i < snapshotCount; i++) {
 182         listenersSnapshot[i]->Observe(message);
 183     }
 184
 185     {
 186         nsAutoLock lock(mLock);
 187         mListening = PR_FALSE;
 188     }
 189
 190     return NS_OK;
 191 }
 192
 193 NS_IMETHODIMP
 194 nsConsoleService::LogStringMessage(const PRUnichar *message)
 195 {
 196     nsConsoleMessage *msg = new nsConsoleMessage(message);
 197     return this->LogMessage(msg);
 198 }
 199
 200 NS_IMETHODIMP
 201 nsConsoleService::GetMessageArray(nsIConsoleMessage ***messages, PRUint32 *count)
 202 {
 203     nsIConsoleMessage **messageArray;
 204
 205     /*
 206      * Lock the whole method, as we don't want anyone mucking with mCurrent or
 207      * mFull while we're copying out the buffer.
 208      */
 209     nsAutoLock lock(mLock);
 210
 211     if (mCurrent == 0 && !mFull) {
 212         /*
 213          * Make a 1-length output array so that nobody gets confused,
 214          * and return a count of 0.  This should result in a 0-length
 215          * array object when called from script.
 216          */
 217         messageArray = (nsIConsoleMessage **)
 218             nsMemory::Alloc(sizeof (nsIConsoleMessage *));
 219         *messageArray = nsnull;
 220         *messages = messageArray;
 221         *count = 0;
 222
 223         return NS_OK;
 224     }
 225
 226     PRUint32 resultSize = mFull ? mBufferSize : mCurrent;
 227     messageArray =
 228         (nsIConsoleMessage **)nsMemory::Alloc((sizeof (nsIConsoleMessage *))
 229                                               * resultSize);
 230
 231     if (messageArray == nsnull) {
 232         *messages = nsnull;
 233         *count = 0;
 234         return NS_ERROR_FAILURE;
 235     }
 236
 237     PRUint32 i;
 238     if (mFull) {
 239         for (i = 0; i < mBufferSize; i++) {
 240             // if full, fill the buffer starting from mCurrent (which'll be
 241             // oldest) wrapping around the buffer to the most recent.
 242             messageArray[i] = mMessages[(mCurrent + i) % mBufferSize];
 243             NS_ADDREF(messageArray[i]);
 244         }
 245     } else {
 246         for (i = 0; i < mCurrent; i++) {
 247             messageArray[i] = mMessages[i];
 248             NS_ADDREF(messageArray[i]);
 249         }
 250     }
 251     *count = resultSize;
 252     *messages = messageArray;
 253
 254     return NS_OK;
 255 }
 256
 257 NS_IMETHODIMP
 258 nsConsoleService::RegisterListener(nsIConsoleListener *listener) {
 259     nsresult rv;
 260
 261     /*
 262      * Store a threadsafe proxy to the listener rather than the
 263      * listener itself; we want the console service to be callable
 264      * from any thread, but listeners can be implemented in
 265      * thread-specific ways, and we always want to call them on their
 266      * originating thread.  JavaScript is the motivating example.
 267      */
 268     nsCOMPtr<nsIConsoleListener> proxiedListener;
 269
 270     rv = GetProxyForListener(listener, getter_AddRefs(proxiedListener));
 271     if (NS_FAILED(rv))
 272         return rv;
 273
 274     {
 275         nsAutoLock lock(mLock);
 276         nsISupportsKey key(listener);
 277
 278         /*
 279          * Put the proxy event listener into a hashtable using the *real*
 280          * listener as the key.
 281          *
 282          * This is necessary because proxy objects do *not* maintain
 283          * nsISupports identity.  Therefore, since GetProxyForListener(...)
 284          * can return different proxies for the same object (see bug #85831)
 285          * we need to use the real object as the unique key...
 286          */
 287         mListeners.Put(&key, proxiedListener);
 288     }
 289     return NS_OK;
 290 }
 291
 292 NS_IMETHODIMP
 293 nsConsoleService::UnregisterListener(nsIConsoleListener *listener) {
 294     nsAutoLock lock(mLock);
 295
 296     nsISupportsKey key(listener);
 297     mListeners.Remove(&key);
 298     return NS_OK;
 299 }
 300
 301 nsresult
 302 nsConsoleService::GetProxyForListener(nsIConsoleListener* aListener,
 303                                       nsIConsoleListener** aProxy)
 304 {
 305     /*
 306      * Would it be better to catch that case and leave the listener unproxied?
 307      */
 308     return NS_GetProxyForObject(NS_PROXY_TO_CURRENT_THREAD,
 309                                 NS_GET_IID(nsIConsoleListener),
 310                                 aListener,
 311                                 NS_PROXY_ASYNC | NS_PROXY_ALWAYS,
 312                                 (void**) aProxy);
 313 }
 314
 315 NS_IMETHODIMP
 316 nsConsoleService::Reset()
 317 {
 318     /*
 319      * Make sure nobody trips into the buffer while it's being reset
 320      */
 321     nsAutoLock lock(mLock);
 322
 323     mCurrent = 0;
 324     mFull = PR_FALSE;
 325
 326     /*
 327      * Free all messages stored so far (cf. destructor)
 328      */
 329     for (PRUint32 i = 0; i < mBufferSize && mMessages[i] != nsnull; i++)
 330         NS_RELEASE(mMessages[i]);
 331
 332     return NS_OK;
 333 }