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)

Author: sipa

src/bitcoind.cpp

@@ -128,6 +128,26 @@ bool AppInit(int argc, char* argv[])
             fprintf(stderr, "Error: There is no RPC client functionality in bitcoind anymore. Use the bitcoin-cli utility instead.\n");
             exit(EXIT_FAILURE);
         }
+        // -server defaults to true for bitcoind but not for the GUI so do this here
+        SoftSetBoolArg("-server", true);
+        // Set this early so that parameter interactions go to console
+        InitLogging();
+        InitParameterInteraction();
+        if (!AppInitBasicSetup())
+        {
+            // InitError will have been called with detailed error, which ends up on console
+            exit(1);
+        }
+        if (!AppInitParameterInteraction())
+        {
+            // InitError will have been called with detailed error, which ends up on console
+            exit(1);
+        }
+        if (!AppInitSanityChecks())
+        {
+            // InitError will have been called with detailed error, which ends up on console
+            exit(1);
+        }
         if (GetBoolArg("-daemon", false))
         {
 #if HAVE_DECL_DAEMON
@@ -143,12 +163,8 @@ bool AppInit(int argc, char* argv[])
             return false;
 #endif // HAVE_DECL_DAEMON
         }
-        SoftSetBoolArg("-server", true);
 
-        // Set this early so that parameter interactions go to console
-        InitLogging();
-        InitParameterInteraction();
-        fRet = AppInit2(threadGroup, scheduler);
+        fRet = AppInitMain(threadGroup, scheduler);
     }
     catch (const std::exception& e) {
         PrintExceptionContinue(&e, "AppInit()");

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))

src/init.h

@@ -25,7 +25,30 @@ void Shutdown();
 void InitLogging();
 //!Parameter interaction: change current parameters depending on various rules
 void InitParameterInteraction();
-bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler);
+
+/** Initialize bitcoin core: Basic context setup.
+ *  @note This can be done before daemonization.
+ *  @pre Parameters should be parsed and config file should be read.
+ */
+bool AppInitBasicSetup();
+/**
+ * Initialization: parameter interaction.
+ * @note This can be done before daemonization.
+ * @pre Parameters should be parsed and config file should be read, AppInitBasicSetup should have been called.
+ */
+bool AppInitParameterInteraction();
+/**
+ * Initialization sanity checks: ecc init, sanity checks, dir lock.
+ * @note This can be done before daemonization.
+ * @pre Parameters should be parsed and config file should be read, AppInitParameterInteraction should have been called.
+ */
+bool AppInitSanityChecks();
+/**
+ * Bitcoin core main initialization.
+ * @note This should only be done after daemonization.
+ * @pre Parameters should be parsed and config file should be read, AppInitSanityChecks should have been called.
+ */
+bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler);
 
 /** The help message mode determines what help message to show */
 enum HelpMessageMode {

src/qt/bitcoin.cpp

@@ -268,7 +268,22 @@ void BitcoinCore::initialize()
     try
     {
         qDebug() << __func__ << ": Running AppInit2 in thread";
-        int rv = AppInit2(threadGroup, scheduler);
+        if (!AppInitBasicSetup())
+        {
+            Q_EMIT initializeResult(false);
+            return;
+        }
+        if (!AppInitParameterInteraction())
+        {
+            Q_EMIT initializeResult(false);
+            return;
+        }
+        if (!AppInitSanityChecks())
+        {
+            Q_EMIT initializeResult(false);
+            return;
+        }
+        int rv = AppInitMain(threadGroup, scheduler);
         Q_EMIT initializeResult(rv);
     } catch (const std::exception& e) {
         handleRunawayException(&e);

src/util.cpp

@@ -107,7 +107,6 @@ map<string, vector<string> > mapMultiArgs;
 bool fDebug = false;
 bool fPrintToConsole = false;
 bool fPrintToDebugLog = true;
-bool fServer = false;
 string strMiscWarning;
 bool fLogTimestamps = DEFAULT_LOGTIMESTAMPS;
 bool fLogTimeMicros = DEFAULT_LOGTIMEMICROS;

src/util.h

@@ -46,7 +46,6 @@ extern std::map<std::string, std::vector<std::string> > mapMultiArgs;
 extern bool fDebug;
 extern bool fPrintToConsole;
 extern bool fPrintToDebugLog;
-extern bool fServer;
 extern std::string strMiscWarning;
 extern bool fLogTimestamps;
 extern bool fLogTimeMicros;