Use the system TID as the thread identifier

This uses the system TID as the LO thread identifier for Linux,
IOS and macOS, just as the Windows backend already does. While at
it use pthread functions on Linux, FreeBSD and MacOS to set the
thread name.

We already depend on MacOS 10.6 for dispatch support and Linux
supports pthread_setname_np since glibc 2.12, which is included in
our baseline. SYS_gettid is available since Linux 2.4.11.

I just copied the FreeBSD info from stackoverflow, while at it.

Change-Id: I39cdd09e952c0a2286d39f938c64b2d2d2f1ef91
Reviewed-on: https://gerrit.libreoffice.org/42071Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>

sal/osl/unx/thread.cxx

@@ -42,10 +42,7 @@
 #endif
 
 #if defined LINUX && ! defined __FreeBSD_kernel__
-#include <sys/prctl.h>
-#ifndef PR_SET_NAME
-#define PR_SET_NAME 15
-#endif
+#include <sys/syscall.h>
 #endif
 
 /****************************************************************************
@@ -80,7 +77,7 @@
 typedef struct osl_thread_impl_st
 {
     pthread_t           m_hThread;
-    sal_uInt16          m_Ident; /* @@@ see TODO @@@ */
+    oslThreadIdentifier m_Ident; /* @@@ see TODO @@@ */
     short               m_Flags;
     oslWorkerFunction   m_WorkerFunction;
     void*               m_pData;
@@ -135,9 +132,9 @@ static oslThread osl_thread_create_Impl (
     oslWorkerFunction pWorker, void * pThreadData, short nFlags);
 
 /* @@@ see TODO @@@ */
-static sal_uInt16 insertThreadId (pthread_t hThread);
-static sal_uInt16 lookupThreadId (pthread_t hThread);
-static void       removeThreadId (pthread_t hThread);
+static oslThreadIdentifier insertThreadId (pthread_t hThread);
+static oslThreadIdentifier lookupThreadId (pthread_t hThread);
+static void                removeThreadId (pthread_t hThread);
 
 static void osl_thread_init_Impl()
 {
@@ -532,12 +529,25 @@ void SAL_CALL osl_yieldThread()
     sched_yield();
 }
 
-void SAL_CALL osl_setThreadName(char const * name) {
+void SAL_CALL osl_setThreadName(char const * name)
+{
+    assert( name );
 #if defined LINUX && ! defined __FreeBSD_kernel__
-    if (prctl(PR_SET_NAME, reinterpret_cast<unsigned long>(name), 0, 0, 0) != 0) {
-        int e = errno;
-        SAL_WARN("sal.osl", "prctl(PR_SET_NAME) failed with errno " << e);
-    }
+    const int LINUX_THREAD_NAME_MAXLEN = 15;
+    if ( strlen( name ) > LINUX_THREAD_NAME_MAXLEN )
+        SAL_INFO( "sal.osl", "osl_setThreadName truncated thread name to "
+                  << LINUX_THREAD_NAME_MAXLEN << " chars from name '"
+                  << name << "'" );
+    char shortname[ LINUX_THREAD_NAME_MAXLEN + 1 ];
+    shortname[ LINUX_THREAD_NAME_MAXLEN ] = '\0';
+    strncpy( shortname, name, LINUX_THREAD_NAME_MAXLEN );
+    int err = pthread_setname_np( pthread_self(), shortname );
+    if ( 0 != err )
+        SAL_WARN("sal.osl", "pthread_setname_np failed with errno " << err);
+#elif defined __FreeBSD_kernel__
+    pthread_setname_np( pthread_self(), name );
+#elif defined MACOSX || defined IOS
+    pthread_setname_np( name );
 #else
     (void) name;
 #endif
@@ -547,9 +557,9 @@ void SAL_CALL osl_setThreadName(char const * name) {
 
 struct HashEntry
 {
-    pthread_t         Handle;
-    sal_uInt16        Ident;
-    HashEntry *       Next;
+    pthread_t            Handle;
+    oslThreadIdentifier  Ident;
+    HashEntry *          Next;
 };
 
 static HashEntry* HashTable[31];
@@ -557,7 +567,9 @@ static int HashSize = SAL_N_ELEMENTS(HashTable);
 
 static pthread_mutex_t HashLock = PTHREAD_MUTEX_INITIALIZER;
 
-static sal_uInt16 LastIdent = 0;
+#if ! (defined LINUX || defined MACOSX || defined IOS)
+static oslThreadIdentifier LastIdent = 0;
+#endif
 
 namespace {
 
@@ -566,7 +578,7 @@ std::size_t HASHID(pthread_t x)
 
 }
 
-static sal_uInt16 lookupThreadId (pthread_t hThread)
+static oslThreadIdentifier lookupThreadId (pthread_t hThread)
 {
     HashEntry *pEntry;
 
@@ -588,7 +600,7 @@ static sal_uInt16 lookupThreadId (pthread_t hThread)
     return 0;
 }
 
-static sal_uInt16 insertThreadId (pthread_t hThread)
+static oslThreadIdentifier insertThreadId (pthread_t hThread)
 {
     HashEntry *pEntry, *pInsert = nullptr;
 
@@ -611,12 +623,28 @@ static sal_uInt16 insertThreadId (pthread_t hThread)
 
         pEntry->Handle = hThread;
 
-        ++ LastIdent;
-
-        if ( LastIdent == 0 )
+#if defined LINUX && ! defined __FreeBSD_kernel__
+        long lin_tid = syscall(SYS_gettid);
+        if (lin_tid <= 0 || lin_tid > SAL_MAX_UINT32)
+            std::abort();
+        pEntry->Ident = static_cast<pid_t>(lin_tid);
+#elif defined MACOSX || defined IOS
+        // currently the value of pthread_threadid_np is the same then
+        // syscall(SYS_thread_selfid), which returns an int as the TID.
+        // may change, as the syscall interface was deprecated.
+        uint64_t mac_tid;
+        pthread_threadid_np(nullptr, &mac_tid);
+        if (mac_tid > SAL_MAX_UINT32)
+            std::abort();
+        pEntry->Ident = mac_tid;
+#else
+        ++LastIdent;
+        if (0 == LastIdent)
             LastIdent = 1;
-
-        pEntry->Ident  = LastIdent;
+        pEntry->Ident = LastIdent;
+#endif
+        if (0 == pEntry->Ident)
+            std::abort();
 
         if (pInsert)
             pInsert->Next = pEntry;
@@ -661,7 +689,7 @@ static void removeThreadId (pthread_t hThread)
 oslThreadIdentifier SAL_CALL osl_getThreadIdentifier(oslThread Thread)
 {
     Thread_Impl* pImpl= static_cast<Thread_Impl*>(Thread);
-    sal_uInt16   Ident;
+    oslThreadIdentifier Ident;
 
     if (pImpl)
         Ident = pImpl->m_Ident;
@@ -676,7 +704,7 @@ oslThreadIdentifier SAL_CALL osl_getThreadIdentifier(oslThread Thread)
             Ident = insertThreadId (current);
     }
 
-    return (oslThreadIdentifier)Ident;
+    return Ident;
 }
 
 /*****************************************************************************