Merge #9010: Split up AppInit2 into multiple phases, daemonize after datadir lock errors

deec83f init: Get rid of fServer flag (Wladimir J. van der Laan)
16ca0bf init: Try to aquire datadir lock before and after daemonization (Wladimir J. van der Laan)
0cc8b6b init: Split up AppInit2 into multiple phases (Wladimir J. van der Laan)

src/init.cpp

@@ -780,10 +780,17 @@ void InitLogging()
     LogPrintf("Bitcoin version %s\n", FormatFullVersion());
 }
 
-/** Initialize bitcoin.
- *  @pre Parameters should be parsed and config file should be read.
- */
-bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
+namespace { // Variables internal to initialization process only
+
+ServiceFlags nRelevantServices = NODE_NETWORK;
+int nMaxConnections;
+int nUserMaxConnections;
+int nFD;
+ServiceFlags nLocalServices = NODE_NETWORK;
+
+}
+
+bool AppInitBasicSetup()
 {
     // ********************************************************* Step 1: setup
 #ifdef _MSC_VER
@@ -835,9 +842,13 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     // Ignore SIGPIPE, otherwise it will bring the daemon down if the client closes unexpectedly
     signal(SIGPIPE, SIG_IGN);
 #endif
+    return true;
+}
 
-    // ********************************************************* Step 2: parameter interactions
+bool AppInitParameterInteraction()
+{
     const CChainParams& chainparams = Params();
+    // ********************************************************* Step 2: parameter interactions
 
     // also see: InitParameterInteraction()
 
@@ -849,12 +860,12 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
 
     // Make sure enough file descriptors are available
     int nBind = std::max((int)mapArgs.count("-bind") + (int)mapArgs.count("-whitebind"), 1);
-    int nUserMaxConnections = GetArg("-maxconnections", DEFAULT_MAX_PEER_CONNECTIONS);
-    int nMaxConnections = std::max(nUserMaxConnections, 0);
+    nUserMaxConnections = GetArg("-maxconnections", DEFAULT_MAX_PEER_CONNECTIONS);
+    nMaxConnections = std::max(nUserMaxConnections, 0);
 
     // Trim requested connection counts, to fit into system limitations
     nMaxConnections = std::max(std::min(nMaxConnections, (int)(FD_SETSIZE - nBind - MIN_CORE_FILEDESCRIPTORS)), 0);
-    int nFD = RaiseFileDescriptorLimit(nMaxConnections + MIN_CORE_FILEDESCRIPTORS);
+    nFD = RaiseFileDescriptorLimit(nMaxConnections + MIN_CORE_FILEDESCRIPTORS);
     if (nFD < MIN_CORE_FILEDESCRIPTORS)
         return InitError(_("Not enough file descriptors available."));
     nMaxConnections = std::min(nFD - MIN_CORE_FILEDESCRIPTORS, nMaxConnections);
@@ -912,8 +923,6 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     else if (nScriptCheckThreads > MAX_SCRIPTCHECK_THREADS)
         nScriptCheckThreads = MAX_SCRIPTCHECK_THREADS;
 
-    fServer = GetBoolArg("-server", false);
-
     // block pruning; get the amount of disk space (in MiB) to allot for block & undo files
     int64_t nSignedPruneTarget = GetArg("-prune", 0) * 1024 * 1024;
     if (nSignedPruneTarget < 0) {
@@ -969,9 +978,6 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     // Option to startup with mocktime set (used for regression testing):
     SetMockTime(GetArg("-mocktime", 0)); // SetMockTime(0) is a no-op
 
-    ServiceFlags nLocalServices = NODE_NETWORK;
-    ServiceFlags nRelevantServices = NODE_NETWORK;
-
     if (GetBoolArg("-peerbloomfilters", DEFAULT_PEERBLOOMFILTERS))
         nLocalServices = ServiceFlags(nLocalServices | NODE_BLOOM);
 
@@ -1020,17 +1026,11 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
             }
         }
     }
+    return true;
+}
 
-    // ********************************************************* Step 4: application initialization: dir lock, daemonize, pidfile, debug log
-
-    // Initialize elliptic curve code
-    ECC_Start();
-    globalVerifyHandle.reset(new ECCVerifyHandle());
-
-    // Sanity check
-    if (!InitSanityCheck())
-        return InitError(strprintf(_("Initialization sanity check failed. %s is shutting down."), _(PACKAGE_NAME)));
-
+static bool LockDataDirectory(bool probeOnly)
+{
     std::string strDataDir = GetDataDir().string();
 
     // Make sure only a single Bitcoin process is using the data directory.
@@ -1040,11 +1040,45 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
 
     try {
         static boost::interprocess::file_lock lock(pathLockFile.string().c_str());
-        if (!lock.try_lock())
+        if (!lock.try_lock()) {
             return InitError(strprintf(_("Cannot obtain a lock on data directory %s. %s is probably already running."), strDataDir, _(PACKAGE_NAME)));
+        }
+        if (probeOnly) {
+            lock.unlock();
+        }
     } catch(const boost::interprocess::interprocess_exception& e) {
         return InitError(strprintf(_("Cannot obtain a lock on data directory %s. %s is probably already running.") + " %s.", strDataDir, _(PACKAGE_NAME), e.what()));
     }
+    return true;
+}
+
+bool AppInitSanityChecks()
+{
+    // ********************************************************* Step 4: sanity checks
+
+    // Initialize elliptic curve code
+    ECC_Start();
+    globalVerifyHandle.reset(new ECCVerifyHandle());
+
+    // Sanity check
+    if (!InitSanityCheck())
+        return InitError(strprintf(_("Initialization sanity check failed. %s is shutting down."), _(PACKAGE_NAME)));
+
+    // Probe the data directory lock to give an early error message, if possible
+    return LockDataDirectory(true);
+}
+
+bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
+{
+    const CChainParams& chainparams = Params();
+    // ********************************************************* Step 4a: application initialization
+    // After daemonization get the data directory lock again and hold on to it until exit
+    // This creates a slight window for a race condition to happen, however this condition is harmless: it
+    // will at most make us exit without printing a message to console.
+    if (!LockDataDirectory(false)) {
+        // Detailed error printed inside LockDataDirectory
+        return false;
+    }
 
 #ifndef WIN32
     CreatePidFile(GetPidFile(), getpid());
@@ -1058,7 +1092,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     if (!fLogTimestamps)
         LogPrintf("Startup time: %s\n", DateTimeStrFormat("%Y-%m-%d %H:%M:%S", GetTime()));
     LogPrintf("Default data directory %s\n", GetDefaultDataDir().string());
-    LogPrintf("Using data directory %s\n", strDataDir);
+    LogPrintf("Using data directory %s\n", GetDataDir().string());
     LogPrintf("Using config file %s\n", GetConfigFile(GetArg("-conf", BITCOIN_CONF_FILENAME)).string());
     LogPrintf("Using at most %i connections (%i file descriptors available)\n", nMaxConnections, nFD);
 
@@ -1077,7 +1111,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
      * that the server is there and will be ready later).  Warmup mode will
      * be disabled when initialisation is finished.
      */
-    if (fServer)
+    if (GetBoolArg("-server", false))
     {
         uiInterface.InitMessage.connect(SetRPCWarmupStatus);
         if (!AppInitServers(threadGroup))