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 "nsSupportsArray.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_QUERY_INTERFACE1_CI(nsConsoleService, nsIConsoleService)
  59 NS_IMPL_CI_INTERFACE_GETTER1(nsConsoleService, nsIConsoleService)
  60
  61 nsConsoleService::nsConsoleService()
  62     : mMessages(nsnull), mCurrent(0), mFull(PR_FALSE), mListening(PR_FALSE), mLock(nsnull)
  63 {
  64     // XXX grab this from a pref!
  65     // hm, but worry about circularity, bc we want to be able to report
  66     // prefs errs...
  67     mBufferSize = 250;
  68 }
  69
  70 nsConsoleService::~nsConsoleService()
  71 {
  72     PRUint32 i = 0;
  73     while (i < mBufferSize && mMessages[i] != nsnull) {
  74         NS_RELEASE(mMessages[i]);
  75         i++;
  76     }
  77
  78 #ifdef DEBUG_mccabe
  79     if (mListeners.Count() != 0) {
  80         fprintf(stderr,
  81             "WARNING - %d console error listeners still registered!\n"
  82             "More calls to nsIConsoleService::UnregisterListener needed.\n",
  83             mListeners.Count());
  84     }
  85
  86 #endif
  87
  88     if (mMessages)
  89         nsMemory::Free(mMessages);
  90     if (mLock)
  91         PR_DestroyLock(mLock);
  92 }
  93
  94 nsresult
  95 nsConsoleService::Init()
  96 {
  97     mMessages = (nsIConsoleMessage **)
  98         nsMemory::Alloc(mBufferSize * sizeof(nsIConsoleMessage *));
  99     if (!mMessages)
 100         return NS_ERROR_OUT_OF_MEMORY;
 101
 102     // Array elements should be 0 initially for circular buffer algorithm.
 103     memset(mMessages, 0, mBufferSize * sizeof(nsIConsoleMessage *));
 104
 105     mLock = PR_NewLock();
 106     if (!mLock)
 107         return NS_ERROR_OUT_OF_MEMORY;
 108
 109     return NS_OK;
 110 }
 111
 112 static PRBool PR_CALLBACK snapshot_enum_func(nsHashKey *key, void *data, void* closure)
 113 {
 114     nsISupportsArray *array = (nsISupportsArray *)closure;
 115
 116     // Copy each element into the temporary nsSupportsArray...
 117     array->AppendElement((nsISupports*)data);
 118     return PR_TRUE;
 119 }
 120
 121 // nsIConsoleService methods
 122 NS_IMETHODIMP
 123 nsConsoleService::LogMessage(nsIConsoleMessage *message)
 124 {
 125     if (message == nsnull)
 126         return NS_ERROR_INVALID_ARG;
 127
 128     nsSupportsArray listenersSnapshot;
 129     nsIConsoleMessage *retiredMessage;
 130
 131     NS_ADDREF(message); // early, in case it's same as replaced below.
 132
 133     /*
 134      * Lock while updating buffer, and while taking snapshot of
 135      * listeners array.
 136      */
 137     {
 138         nsAutoLock lock(mLock);
 139
 140         /*
 141          * If there's already a message in the slot we're about to replace,
 142          * we've wrapped around, and we need to release the old message.  We
 143          * save a pointer to it, so we can release below outside the lock.
 144          */
 145         retiredMessage = mMessages[mCurrent];
 146
 147         mMessages[mCurrent++] = message;
 148         if (mCurrent == mBufferSize) {
 149             mCurrent = 0; // wrap around.
 150             mFull = PR_TRUE;
 151         }
 152
 153         /*
 154          * Copy the listeners into the snapshot array - in case a listener
 155          * is removed during an Observe(...) notification...
 156          */
 157         mListeners.Enumerate(snapshot_enum_func, &listenersSnapshot);
 158     }
 159     if (retiredMessage != nsnull)
 160         NS_RELEASE(retiredMessage);
 161
 162     /*
 163      * Iterate through any registered listeners and tell them about
 164      * the message.  We use the mListening flag to guard against
 165      * recursive message logs.  This could sometimes result in
 166      * listeners being skipped because of activity on other threads,
 167      * when we only care about the recursive case.
 168      */
 169     nsCOMPtr<nsIConsoleListener> listener;
 170     nsresult rv;
 171     nsresult returned_rv;
 172     PRUint32 snapshotCount;
 173     rv = listenersSnapshot.Count(&snapshotCount);
 174     if (NS_FAILED(rv))
 175         return rv;
 176
 177     {
 178         nsAutoLock lock(mLock);
 179         if (mListening)
 180             return NS_OK;
 181         mListening = PR_TRUE;
 182     }
 183
 184     returned_rv = NS_OK;
 185     for (PRUint32 i = 0; i < snapshotCount; i++) {
 186         rv = listenersSnapshot.GetElementAt(i, getter_AddRefs(listener));
 187         if (NS_FAILED(rv)) {
 188             returned_rv = rv;
 189             break; // fall thru to mListening restore code below.
 190         }
 191         listener->Observe(message);
 192     }
 193
 194     {
 195         nsAutoLock lock(mLock);
 196         mListening = PR_FALSE;
 197     }
 198
 199     return returned_rv;
 200 }
 201
 202 NS_IMETHODIMP
 203 nsConsoleService::LogStringMessage(const PRUnichar *message)
 204 {
 205     nsConsoleMessage *msg = new nsConsoleMessage(message);
 206     return this->LogMessage(msg);
 207 }
 208
 209 NS_IMETHODIMP
 210 nsConsoleService::GetMessageArray(nsIConsoleMessage ***messages, PRUint32 *count)
 211 {
 212     nsIConsoleMessage **messageArray;
 213
 214     /*
 215      * Lock the whole method, as we don't want anyone mucking with mCurrent or
 216      * mFull while we're copying out the buffer.
 217      */
 218     nsAutoLock lock(mLock);
 219
 220     if (mCurrent == 0 && !mFull) {
 221         /*
 222          * Make a 1-length output array so that nobody gets confused,
 223          * and return a count of 0.  This should result in a 0-length
 224          * array object when called from script.
 225          */
 226         messageArray = (nsIConsoleMessage **)
 227             nsMemory::Alloc(sizeof (nsIConsoleMessage *));
 228         *messageArray = nsnull;
 229         *messages = messageArray;
 230         *count = 0;
 231
 232         return NS_OK;
 233     }
 234
 235     PRUint32 resultSize = mFull ? mBufferSize : mCurrent;
 236     messageArray =
 237         (nsIConsoleMessage **)nsMemory::Alloc((sizeof (nsIConsoleMessage *))
 238                                               * resultSize);
 239
 240     if (messageArray == nsnull) {
 241         *messages = nsnull;
 242         *count = 0;
 243         return NS_ERROR_FAILURE;
 244     }
 245
 246     PRUint32 i;
 247     if (mFull) {
 248         for (i = 0; i < mBufferSize; i++) {
 249             // if full, fill the buffer starting from mCurrent (which'll be
 250             // oldest) wrapping around the buffer to the most recent.
 251             messageArray[i] = mMessages[(mCurrent + i) % mBufferSize];
 252             NS_ADDREF(messageArray[i]);
 253         }
 254     } else {
 255         for (i = 0; i < mCurrent; i++) {
 256             messageArray[i] = mMessages[i];
 257             NS_ADDREF(messageArray[i]);
 258         }
 259     }
 260     *count = resultSize;
 261     *messages = messageArray;
 262
 263     return NS_OK;
 264 }
 265
 266 NS_IMETHODIMP
 267 nsConsoleService::RegisterListener(nsIConsoleListener *listener) {
 268     nsresult rv;
 269
 270     /*
 271      * Store a threadsafe proxy to the listener rather than the
 272      * listener itself; we want the console service to be callable
 273      * from any thread, but listeners can be implemented in
 274      * thread-specific ways, and we always want to call them on their
 275      * originating thread.  JavaScript is the motivating example.
 276      */
 277     nsCOMPtr<nsIConsoleListener> proxiedListener;
 278
 279     rv = GetProxyForListener(listener, getter_AddRefs(proxiedListener));
 280     if (NS_FAILED(rv))
 281         return rv;
 282
 283     {
 284         nsAutoLock lock(mLock);
 285         nsISupportsKey key(listener);
 286
 287         /*
 288          * Put the proxy event listener into a hashtable using the *real*
 289          * listener as the key.
 290          *
 291          * This is necessary because proxy objects do *not* maintain
 292          * nsISupports identity.  Therefore, since GetProxyForListener(...)
 293          * can return different proxies for the same object (see bug #85831)
 294          * we need to use the real object as the unique key...
 295          */
 296         mListeners.Put(&key, proxiedListener);
 297     }
 298     return NS_OK;
 299 }
 300
 301 NS_IMETHODIMP
 302 nsConsoleService::UnregisterListener(nsIConsoleListener *listener) {
 303     nsAutoLock lock(mLock);
 304
 305     nsISupportsKey key(listener);
 306     mListeners.Remove(&key);
 307     return NS_OK;
 308 }
 309
 310 nsresult
 311 nsConsoleService::GetProxyForListener(nsIConsoleListener* aListener,
 312                                       nsIConsoleListener** aProxy)
 313 {
 314     /*
 315      * Would it be better to catch that case and leave the listener unproxied?
 316      */
 317     return NS_GetProxyForObject(NS_PROXY_TO_CURRENT_THREAD,
 318                                 NS_GET_IID(nsIConsoleListener),
 319                                 aListener,
 320                                 NS_PROXY_ASYNC | NS_PROXY_ALWAYS,
 321                                 (void**) aProxy);
 322 }
 323
 324 NS_IMETHODIMP
 325 nsConsoleService::Reset()
 326 {
 327     /*
 328      * Make sure nobody trips into the buffer while it's being reset
 329      */
 330     nsAutoLock lock(mLock);
 331
 332     mCurrent = 0;
 333     mFull = PR_FALSE;
 334
 335     /*
 336      * Free all messages stored so far (cf. destructor)
 337      */
 338     for (PRUint32 i = 0; i < mBufferSize && mMessages[i] != nsnull; i++)
 339         NS_RELEASE(mMessages[i]);
 340
 341     return NS_OK;
 342 }