tight: multithreaded

Author: Volodymyr Samokhatko

include/rfb/rfb.h

@@ -84,6 +84,10 @@ typedef UINT32 in_addr_t;
 #endif
 #endif
 
+/* Maximum number of threads to use for multithreaded encoding, regardless of
+   the CPU count */
+#define MAX_ENCODING_THREADS 8
+
 struct _rfbClientRec;
 struct _rfbScreenInfo;
 struct rfbCursor;
@@ -372,6 +376,8 @@ typedef struct _rfbScreenInfo
 #ifdef LIBVNCSERVER_HAVE_LIBZ
     rfbSetXCutTextUTF8ProcPtr setXCutTextUTF8;
 #endif
+    rfbBool rfbMT;
+    int rfbNumThreads;
 } rfbScreenInfo, *rfbScreenInfoPtr;
 
 
@@ -705,6 +711,16 @@ typedef struct _rfbClientRec {
     rfbBool tightUsePixelFormat24;
     void *tightTJ;
     int tightPngDstDataLen;
+
+    /* Multithreaded tight encoding. */
+
+    rfbBool threadInit;
+#ifdef LIBVNCSERVER_HAVE_LIBPTHREAD
+    pthread_t thnd[MAX_ENCODING_THREADS];
+#elif defined(LIBVNCSERVER_HAVE_WIN32THREADS)
+    uintptr_t thnd[MAX_ENCODING_THREADS];
+#endif
+
 #endif
 #endif
 } rfbClientRec, *rfbClientPtr;

src/libvncserver/cargs.c

@@ -60,6 +60,13 @@ rfbUsage(void)
     fprintf(stderr, "-listenv6 ipv6addr     listen for IPv6 connections only on network interface with\n");
     fprintf(stderr, "                       addr ipv6addr. '-listen localhost' and hostname work too.\n");
 #endif
+#if defined(LIBVNCSERVER_HAVE_LIBPTHREAD) || defined(LIBVNCSERVER_HAVE_WIN32THREADS)
+    fprintf(stderr, "-nomt                  disable multithreaded Tight encoding\n");
+    fprintf(stderr, "-nthreads N            specify number of threads (1 <= N <= %d) to use with\n",
+         MAX_ENCODING_THREADS);
+    fprintf(stderr, "                       multithreaded Tight encoding [default: 1 per CPU core,\n");
+    fprintf(stderr, "                       max. %d]\n", MAX_ENCODING_THREADS);
+#endif
 
     for(extension=rfbGetExtensionIterator();extension;extension=extension->next)
 	if(extension->usage)
@@ -202,6 +209,20 @@ rfbProcessArguments(rfbScreenInfoPtr rfbScreen,int* argc, char *argv[])
 	    }
 	    rfbScreen->listen6Interface = argv[++i];
 #endif
+#if defined(LIBVNCSERVER_HAVE_LIBPTHREAD) || defined(LIBVNCSERVER_HAVE_WIN32THREADS)
+        } else if (strcmp(argv[i], "-nomt") == 0) {
+            rfbScreen->rfbMT = FALSE;
+        } else if (strcmp(argv[i], "-nthreads") == 0) {
+            if (i + 1 >= *argc) {
+                rfbUsage();
+                return FALSE;
+            }
+            rfbScreen->rfbNumThreads = atoi(argv[++i]);
+            if (rfbScreen->rfbNumThreads < 1 || rfbScreen->rfbNumThreads > MAX_ENCODING_THREADS) {
+                rfbUsage();
+                return FALSE;
+            }
+#endif
 #ifdef LIBVNCSERVER_WITH_WEBSOCKETS
         } else if (strcmp(argv[i], "-sslkeyfile") == 0) {  /* -sslkeyfile sslkeyfile */
             if (i + 1 >= *argc) {

src/libvncserver/main.c

@@ -10,6 +10,13 @@
  *  see GPL (latest version) for full details
  */
 
+#include <rfb/rfbconfig.h>
+
+#if LIBVNCSERVER_HAVE_SCHED_H
+#define _GNU_SOURCE
+#include <sched.h>
+#endif
+
 #ifdef __STRICT_ANSI__
 #define _BSD_SOURCE
 #endif
@@ -55,6 +62,42 @@ char rfbEndianTest = (1==0);
 char rfbEndianTest = (1==1);
 #endif
 
+#ifndef min
+inline static int min(int a, int b)
+{
+    return a > b ? b : a;
+}
+#endif
+
+#ifdef __APPLE__
+typedef struct cpu_set {
+    uint64_t    count;
+} cpu_set_t;
+
+static inline void
+CPU_ZERO(cpu_set_t *cs) { cs->count = 0; }
+
+static inline int
+CPU_COUNT(cpu_set_t *cs) { return __builtin_popcountll(cs->count); }
+
+int sched_getaffinity(pid_t pid, size_t cpu_size, cpu_set_t *cpu_set)
+{
+    int32_t core_count = 0;
+    size_t  len = sizeof(core_count);
+    int ret = sysctlbyname("machdep.cpu.core_count", &core_count, &len, 0, 0);
+    if (ret) {
+        rfbErr("error while get core count %d\n", ret);
+        return -1;
+    }
+    cpu_set->count = 0;
+    for (int i = 0; i < core_count; i++) {
+        cpu_set->count |= (1 << i);
+    }
+
+    return 0;
+}
+#endif
+
 /*
  * Protocol extensions
  */
@@ -996,11 +1039,43 @@ rfbScreenInfoPtr rfbGetScreen(int* argc,char** argv,
 
    screen->permitFileTransfer = FALSE;
 
+   screen->rfbMT = TRUE;
+   screen->rfbNumThreads = 0;
+
    if(!rfbProcessArguments(screen,argc,argv)) {
      free(screen);
      return NULL;
    }
 
+#if defined(LIBVNCSERVER_HAVE_LIBPTHREAD) || defined(LIBVNCSERVER_HAVE_WIN32THREADS)
+#if defined(WIN32) || defined(__MINGW32__)
+   DWORD64 dwProcessAffinity, dwSystemAffinity;
+   GetProcessAffinityMask(GetCurrentProcess(), &dwProcessAffinity, &dwSystemAffinity);
+   const int np = __popcnt64(dwProcessAffinity);
+#elif LIBVNCSERVER_HAVE_SCHED_H
+   cpu_set_t cs;
+   CPU_ZERO(&cs);
+   int cpus = -1;
+   if (sched_getaffinity(0, sizeof(cs), &cs) == 0) {
+       cpus = CPU_COUNT(&cs);
+   }
+   const int np = cpus;
+#else
+   const int np = -1;
+#endif
+   if (np == -1 && screen->rfbMT) {
+     rfbLog("WARNING: Could not determine CPU count.  Multithreaded encoding disabled.\n");
+     screen->rfbMT = FALSE;
+   }
+   if (!screen->rfbMT) screen->rfbNumThreads = 1;
+   else if (screen->rfbNumThreads < 1) screen->rfbNumThreads = min(np, 4);
+   if (screen->rfbNumThreads > np) {
+     rfbLog("NOTICE: Encoding thread count has been clamped to CPU count\n");
+     screen->rfbNumThreads = np;
+   }
+#endif
+
+
 #ifdef WIN32
    {
 	   DWORD dummy=255;

src/libvncserver/rfbserver.c

@@ -504,6 +504,15 @@ rfbNewTCPOrUDPClient(rfbScreenInfoPtr rfbScreen,
       }
     }
 
+#ifdef LIBVNCSERVER_HAVE_LIBJPEG
+    /* Multithreaded tight encoding. */
+
+    cl->threadInit = FALSE;
+#if defined(LIBVNCSERVER_HAVE_LIBPTHREAD) || defined(LIBVNCSERVER_HAVE_WIN32THREADS)
+    memset(cl->thnd, 0, sizeof(cl->thnd));
+#endif
+#endif
+
     for(extension = rfbGetExtensionIterator(); extension;
 	    extension=extension->next) {
 	void* data = NULL;