Try to increase file descriptor rlimit if necessary

As the default can be too low, especially on OSX.

src/init.cpp

@@ -28,6 +28,15 @@ using namespace boost;
 CWallet* pwalletMain;
 CClientUIInterface uiInterface;
 
+#ifdef WIN32
+// Win32 LevelDB doesn't use filedescriptors, and the ones used for
+// accessing block files, don't count towards to fd_set size limit
+// anyway.
+#define MIN_CORE_FILEDESCRIPTORS 0
+#else
+#define MIN_CORE_FILEDESCRIPTORS 150
+#endif
+
 // Used to pass flags to the Bind() function
 enum BindFlags {
     BF_NONE         = 0,
@@ -518,6 +527,16 @@ bool AppInit2(boost::thread_group& threadGroup)
         SoftSetBoolArg("-rescan", true);
     }
 
+    // Make sure enough file descriptors are available
+    int nBind = std::max((int)mapArgs.count("-bind"), 1);
+    nMaxConnections = GetArg("-maxconnections", 125);
+    nMaxConnections = std::max(std::min(nMaxConnections, FD_SETSIZE - nBind - MIN_CORE_FILEDESCRIPTORS), 0);
+    int nFD = RaiseFileDescriptorLimit(nMaxConnections + MIN_CORE_FILEDESCRIPTORS);
+    if (nFD < MIN_CORE_FILEDESCRIPTORS)
+        return InitError(_("Not enough file descriptors available."));
+    if (nFD - MIN_CORE_FILEDESCRIPTORS < nMaxConnections)
+        nMaxConnections = nFD - MIN_CORE_FILEDESCRIPTORS;
+
     // ********************************************************* Step 3: parameter-to-internal-flags
 
     fDebug = GetBoolArg("-debug");
@@ -594,6 +613,7 @@ bool AppInit2(boost::thread_group& threadGroup)
         printf("Startup time: %s\n", DateTimeStrFormat("%Y-%m-%d %H:%M:%S", GetTime()).c_str());
     printf("Default data directory %s\n", GetDefaultDataDir().string().c_str());
     printf("Used data directory %s\n", strDataDir.c_str());
+    printf("Using at most %i connections (%i file descriptors available)\n", nMaxConnections, nFD);
     std::ostringstream strErrors;
 
     if (fDaemon)

src/net.cpp

@@ -48,6 +48,7 @@ static CNode* pnodeSync = NULL;
 uint64 nLocalHostNonce = 0;
 static std::vector<SOCKET> vhListenSocket;
 CAddrMan addrman;
+int nMaxConnections = 125;
 
 vector<CNode*> vNodes;
 CCriticalSection cs_vNodes;
@@ -908,7 +909,7 @@ void ThreadSocketHandler()
                 if (nErr != WSAEWOULDBLOCK)
                     printf("socket error accept failed: %d\n", nErr);
             }
-            else if (nInbound >= GetArg("-maxconnections", 125) - MAX_OUTBOUND_CONNECTIONS)
+            else if (nInbound >= nMaxConnections - MAX_OUTBOUND_CONNECTIONS)
             {
                 {
                     LOCK(cs_setservAddNodeAddresses);
@@ -1803,7 +1804,7 @@ void StartNode(boost::thread_group& threadGroup)
 {
     if (semOutbound == NULL) {
         // initialize semaphore
-        int nMaxOutbound = min(MAX_OUTBOUND_CONNECTIONS, (int)GetArg("-maxconnections", 125));
+        int nMaxOutbound = min(MAX_OUTBOUND_CONNECTIONS, nMaxConnections);
         semOutbound = new CSemaphore(nMaxOutbound);
     }
 

src/net.h

@@ -74,6 +74,7 @@ extern bool fDiscover;
 extern uint64 nLocalServices;
 extern uint64 nLocalHostNonce;
 extern CAddrMan addrman;
+extern int nMaxConnections;
 
 extern std::vector<CNode*> vNodes;
 extern CCriticalSection cs_vNodes;

src/util.cpp

@@ -10,6 +10,7 @@
 #endif
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <sys/resource.h>
 #endif
 
 #include "util.h"
@@ -1167,6 +1168,28 @@ bool TruncateFile(FILE *file, unsigned int length) {
 #endif
 }
 
+
+// this function tries to raise the file descriptor limit to the requested number.
+// It returns the actual file descriptor limit (which may be more or less than nMinFD)
+int RaiseFileDescriptorLimit(int nMinFD) {
+#if defined(WIN32)
+    return 2048;
+#else
+    struct rlimit limitFD;
+    if (getrlimit(RLIMIT_NOFILE, &limitFD) != -1) {
+        if (limitFD.rlim_cur < (rlim_t)nMinFD) {
+            limitFD.rlim_cur = nMinFD;
+            if (limitFD.rlim_cur > limitFD.rlim_max)
+                limitFD.rlim_cur = limitFD.rlim_max;
+            setrlimit(RLIMIT_NOFILE, &limitFD);
+            getrlimit(RLIMIT_NOFILE, &limitFD);
+        }
+        return limitFD.rlim_cur;
+    }
+    return nMinFD; // getrlimit failed, assume it's fine
+#endif
+}
+
 // this function tries to make a particular range of a file allocated (corresponding to disk space)
 // it is advisory, and the range specified in the arguments will never contain live data
 void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length) {

src/util.h

@@ -197,6 +197,7 @@ bool WildcardMatch(const std::string& str, const std::string& mask);
 void FileCommit(FILE *fileout);
 int GetFilesize(FILE* file);
 bool TruncateFile(FILE *file, unsigned int length);
+int RaiseFileDescriptorLimit(int nMinFD);
 void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length);
 bool RenameOver(boost::filesystem::path src, boost::filesystem::path dest);
 boost::filesystem::path GetDefaultDataDir();