Replace pthread_self_ulong() with H5TS_thread_id(). The POSIX Threads

implementation ought to be portable to any system that has POSIX
Threads.  On Windows, I use the same API call as before.

src/H5CS.c

@@ -145,11 +145,7 @@ H5CS_print_stack(const H5CS_t *fstack, FILE *stream)
 
     HDfprintf(stream, "HDF5-DIAG: Function stack from %s ", H5_lib_vers_info_g);
     /* try show the process or thread id in multiple processes cases*/
-#ifdef H5_HAVE_THREADSAFE
-    HDfprintf(stream, "thread %lu.", HDpthread_self_ulong());
-#else  /* H5_HAVE_THREADSAFE */
-    HDfprintf(stream, "thread 0.");
-#endif  /* H5_HAVE_THREADSAFE */
+    HDfprintf(stream, "thread %lu.", H5TS_thread_id());
     if(fstack && fstack->nused>0)
         HDfprintf(stream, "  Back trace follows.");
     HDfputc('\n', stream);

src/H5Eint.c

@@ -259,10 +259,8 @@ H5E__walk1_cb(int n, H5E_error1_t *err_desc, void *client_data)
             else
                 HDfprintf(stream, "thread 0");
         } /* end block */
-#elif defined(H5_HAVE_THREADSAFE)
-        HDfprintf(stream, "thread %lu", (unsigned long)HDpthread_self_ulong());
 #else
-        HDfprintf(stream, "thread 0");
+        HDfprintf(stream, "thread %lu", H5TS_thread_id());
 #endif
         HDfprintf(stream, ":\n");
     } /* end if */
@@ -391,10 +389,8 @@ H5E__walk2_cb(unsigned n, const H5E_error2_t *err_desc, void *client_data)
             else
                 HDfprintf(stream, "thread 0");
         } /* end block */
-#elif defined(H5_HAVE_THREADSAFE)
-        HDfprintf(stream, "thread %lu", (unsigned long)HDpthread_self_ulong());
 #else
-        HDfprintf(stream, "thread 0");
+        HDfprintf(stream, "thread %lu", H5TS_thread_id());
 #endif
         HDfprintf(stream, ":\n");
     } /* end if */

src/H5TS.c

@@ -37,6 +37,31 @@ H5TS_key_t H5TS_funcstk_key_g;
 H5TS_key_t H5TS_apictx_key_g;
 H5TS_key_t H5TS_cancel_key_g;
 
+#ifndef H5_HAVE_WIN_THREADS
+
+/* An h5_tid_t is a record of a thread identifier that is
+ * available for reuse.
+ */
+struct _tid;
+typedef struct _tid h5_tid_t;
+
+struct _tid {
+    h5_tid_t *next;
+    unsigned long id;
+};
+
+/* Pointer to first free thread ID record or NULL. */
+static h5_tid_t *tid_next_free = NULL;
+static unsigned long tid_next_id = 0;
+
+/* Mutual exclusion for access to tid_next_free and tid_next_id. */
+static pthread_mutex_t tid_mtx;
+
+/* Key for thread-local storage of the thread ID. */
+static H5TS_key_t tid_key;
+
+#endif /* H5_HAVE_WIN_THREADS */
+
 
 /*--------------------------------------------------------------------------
  * NAME
@@ -68,6 +93,89 @@ H5TS_key_destructor(void *key_val)
 
 #ifndef H5_HAVE_WIN_THREADS
 
+/* When a thread shuts down, put its ID record on the free list. */
+static void
+tid_destructor(void *_v)
+{
+    h5_tid_t *tid = _v;
+
+    if (tid == NULL)
+        return;
+
+    /* XXX I can use mutexes in destructors, right? */
+    /* TBD use an atomic CAS */
+    pthread_mutex_lock(&tid_mtx);
+    tid->next = tid_next_free;
+    tid_next_free = tid;
+    pthread_mutex_unlock(&tid_mtx);
+}
+
+/* Initialize for integer thread identifiers. */
+static void
+tid_init(void)
+{
+    pthread_mutex_init(&tid_mtx, NULL);
+    pthread_key_create(&tid_key, tid_destructor);
+}
+
+/* Return an integer identifier, ID, for the current thread satisfies the
+ * following properties:
+ *
+ * 1 1 <= ID <= ULONG_MAX
+ * 2 The ID is constant over the thread's lifetime.
+ * 3 No two threads share an ID during their lifetimes.
+ * 4 A thread's ID is available for reuse as soon as it is joined.
+ *
+ * ID 0 is reserved.  H5TS_thread_id() returns 0 if the library was not built
+ * with thread safety or if an error prevents it from assigning an ID.
+ */
+unsigned long
+H5TS_thread_id(void)
+{
+    h5_tid_t *tid = pthread_getspecific(tid_key);
+    h5_tid_t proto_tid;
+
+    /* An ID is already assigned. */
+    if (tid != NULL)
+        return tid->id;
+
+    /* An ID is *not* already assigned: reuse an ID that's on the
+     * free list, or else generate a new ID.
+     * 
+     * Allocating memory while holding a mutex is bad form, so
+     * point `tid` at `proto_tid` if we need to allocate some
+     * memory.
+     */
+    pthread_mutex_lock(&tid_mtx);
+    if ((tid = tid_next_free) != NULL)
+        tid_next_free = tid->next;
+    else if (tid_next_id != ULONG_MAX) {
+        tid = &proto_tid;
+        tid->id = ++tid_next_id;
+    }
+    pthread_mutex_unlock(&tid_mtx);
+
+    /* If a prototype ID record was established, copy it to the heap. */
+    if (tid == &proto_tid) {
+        if ((tid = HDmalloc(sizeof(*tid))) != NULL)
+            *tid = proto_tid;
+    }
+
+    if (tid == NULL)
+        return 0;
+
+    /* Finish initializing the ID record and set a thread-local pointer
+     * to it.
+     */
+    tid->next = NULL;
+    if (pthread_setspecific(tid_key, tid) != 0) {
+        tid_destructor(tid);
+        return 0;
+    }
+
+    return tid->id;
+}
+
 /*--------------------------------------------------------------------------
  * NAME
  *    H5TS_pthread_first_thread_init
@@ -104,6 +212,9 @@ H5TS_pthread_first_thread_init(void)
     pthread_cond_init(&H5_g.init_lock.cond_var, NULL);
     H5_g.init_lock.lock_count = 0;
 
+    /* Initialize integer thread identifiers. */
+    tid_init();
+
     /* initialize key for thread-specific error stacks */
     pthread_key_create(&H5TS_errstk_key_g, H5TS_key_destructor);
 
@@ -528,5 +639,13 @@ H5TS_create_thread(void *(*func)(void *), H5TS_attr_t *attr, void *udata)
 
 } /* H5TS_create_thread */
 
+#else  /* H5_HAVE_THREADSAFE */
+
+unsigned long
+H5TS_thread_id(void)
+{
+    return 0;
+}
+
 #endif  /* H5_HAVE_THREADSAFE */
 

src/H5TSprivate.h

@@ -68,7 +68,7 @@ H5_DLL void H5TS_win32_process_exit(void);
 H5_DLL herr_t H5TS_win32_thread_enter(void);
 H5_DLL herr_t H5TS_win32_thread_exit(void);
 
-
+#define H5TS_thread_id() ((unsigned long)GetCurrentThreadId())
 
 #else /* H5_HAVE_WIN_THREADS */
 
@@ -102,6 +102,7 @@ typedef pthread_once_t H5TS_once_t;
 #define H5TS_mutex_init(mutex) pthread_mutex_init(mutex, NULL)
 #define H5TS_mutex_lock_simple(mutex) pthread_mutex_lock(mutex)
 #define H5TS_mutex_unlock_simple(mutex) pthread_mutex_unlock(mutex)
+H5_DLL unsigned long H5TS_thread_id(void);
 
 #endif /* H5_HAVE_WIN_THREADS */
 

src/H5private.h

@@ -1549,11 +1549,6 @@ extern char *strdup(const char *s);
     #define HDpthread_self()    pthread_self()
 #endif /* HDpthread_self */
 
-/* Use this version of pthread_self for printing the thread ID */
-#ifndef HDpthread_self_ulong
-    #define HDpthread_self_ulong()    ((unsigned long)pthread_self())
-#endif /* HDpthread_self_ulong */
-
 /* Macro for "stringizing" an integer in the C preprocessor (use H5_TOSTRING) */
 /* (use H5_TOSTRING, H5_STRINGIZE is just part of the implementation) */
 #define H5_STRINGIZE(x) #x

src/H5win32defs.h

@@ -163,10 +163,6 @@ extern "C" {
 
 /* Non-POSIX functions */
 
-/* Don't use actual pthread_self on Windows because the return
- * type cannot be cast as a ulong like other systems. */
-#define HDpthread_self_ulong() ((unsigned long)GetCurrentThreadId())
-
 #ifndef H5_HAVE_MINGW
 #define HDftruncate(F,L)    _chsize_s(F,L)
 #define HDfseek(F,O,W)      _fseeki64(F,O,W)

test/Makefile.am

@@ -63,7 +63,7 @@ TEST_PROG= testhdf5 \
            flush1 flush2 app_ref enum set_extent ttsafe enc_dec_plist \
            enc_dec_plist_cross_platform getname vfd ros3 s3comms hdfs ntypes \
            dangle dtransform reserved cross_read freespace mf vds file_image \
-           unregister cache_logging cork swmr vol
+           unregister cache_logging cork swmr thread_id vol
 
 # List programs to be built when testing here.
 # error_test and err_compat are built at the same time as the other tests, but executed by testerror.sh.

test/h5test.c

@@ -1172,10 +1172,8 @@ h5_show_hostname(void)
         else
             HDprintf("thread 0.");
     }
-#elif defined(H5_HAVE_THREADSAFE)
-    HDprintf("thread %lu.", HDpthread_self_ulong());
 #else
-    HDprintf("thread 0.");
+    HDprintf("thread %lu.", H5TS_thread_id());
 #endif
 #ifdef H5_HAVE_WIN32_API
 

test/thread_id.c

@@ -0,0 +1,162 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/* Check that a thread ID returned by H5TS_thread_id() possesses the
+ * following properties: 
+ *
+ * 1 ID >= 1.
+ * 2 The ID is constant over the thread's lifetime.
+ * 3 No two threads share an ID during their lifetimes.
+ * 4 A thread's ID is available for reuse as soon as it is joined.
+ */
+#include <err.h>
+
+/*
+ * Include required headers.  This file tests internal library functions,
+ * so we include the private headers here.
+ */
+#include "testhdf5.h"
+
+#define threads_failure(_call, _result) do {                \
+    errx(EXIT_FAILURE, "%s.%d: " #_call ": %s", __func__,   \
+        __LINE__, strerror(_result));                       \
+} while (false)
+
+#if defined(H5_HAVE_THREADSAFE) && !defined(H5_HAVE_WIN_THREADS)
+
+#define NTHREADS 5
+
+static volatile bool failed = false;
+static pthread_barrier_t barrier;
+static bool used[NTHREADS];
+static pthread_mutex_t used_lock;
+
+static void
+atomic_printf(const char *fmt, ...)
+{
+    char buf[80];
+    va_list ap;
+    ssize_t nprinted, nwritten;
+
+    va_start(ap, fmt);
+    nprinted = vsnprintf(buf, sizeof(buf), fmt, ap);
+    va_end(ap);
+
+    if (nprinted == -1)
+        err(EXIT_FAILURE, "%s.%d: vsnprintf", __func__, __LINE__);
+    else if (nprinted >= (ssize_t)sizeof(buf))
+        errx(EXIT_FAILURE, "%s.%d: vsnprintf overflowed", __func__, __LINE__);
+
+    nwritten = write(STDOUT_FILENO, buf, (size_t)nprinted);
+    if (nwritten < nprinted) {
+        errx(EXIT_FAILURE, "%s.%d: write error or short write",
+            __func__, __LINE__);
+    }
+}
+
+/* Each thread runs this routine.  The routine fetches the current
+ * thread's ID, makes sure that it is in the expected range, makes
+ * sure that in this round of testing, no two threads shared the
+ * same ID, 
+ */
+static void *
+thread_main(void H5_ATTR_UNUSED *arg)
+{
+    unsigned long ntid, tid;
+
+    tid = H5TS_thread_id();
+
+    if (tid < 1 || NTHREADS < tid) {
+        atomic_printf("unexpected tid %lu FAIL\n", tid);
+        goto pre_barrier_error;
+    }
+    pthread_mutex_lock(&used_lock);
+    if (used[tid - 1]) {
+        atomic_printf("reused tid %lu FAIL\n", tid);
+        pthread_mutex_unlock(&used_lock);
+        goto pre_barrier_error;
+    }
+    used[tid - 1] = true;
+    pthread_mutex_unlock(&used_lock);
+
+    atomic_printf("tid %lu in [1, %d] PASS\n", tid, NTHREADS);
+    pthread_barrier_wait(&barrier);
+
+    ntid = H5TS_thread_id();
+    if (ntid != tid) {
+        atomic_printf("tid changed from %lu to %lu FAIL\n", tid, ntid);
+        failed = true;
+    }
+    return NULL;
+pre_barrier_error:
+    pthread_barrier_wait(&barrier);
+    failed = true;
+    return NULL;
+}
+
+int
+main(void)
+{
+    int i, rc, times;
+    pthread_t threads[NTHREADS];
+
+    /* Run H5open() to initialize the library's thread-ID freelist,
+     * mutex, etc.
+     */
+    if (H5open() != SUCCEED)
+        errx(EXIT_FAILURE, "%s.%d: H5open failed", __func__, __LINE__);
+
+    if ((rc = pthread_mutex_init(&used_lock, NULL)) == -1)
+        threads_failure(pthread_mutex_init, rc);
+
+    if ((rc = pthread_barrier_init(&barrier, NULL, NTHREADS)) != 0)
+        threads_failure(pthread_barrier_init, rc);
+
+    /* Start the test threads and join them twice to make sure that
+     * the thread IDs are recycled in the second round.
+     */
+    for (times = 0; times < 2; times++) {
+
+        for (i = 0; i < NTHREADS; i++)
+            used[i] = false;    // access synchronized by thread create/join
+
+        for (i = 0; i < NTHREADS; i++) {
+            rc = pthread_create(&threads[i], NULL, thread_main, NULL);
+            if (rc != 0)
+                threads_failure(pthread_create, rc);
+        }
+
+        for (i = 0; i < NTHREADS; i++) {
+            rc = pthread_join(threads[i], NULL);
+            if (rc != 0)
+                threads_failure(pthread_join, rc);
+        }
+
+        for (i = 0; i < NTHREADS; i++) {
+            if (!used[i]) // access synchronized by thread create/join
+                errx(EXIT_FAILURE, "thread ID %d did not run.", i + 1);
+        }
+    }
+    if ((rc = pthread_barrier_destroy(&barrier)) != 0)
+        threads_failure(pthread_barrier_destroy, rc);
+    return failed ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+#else /*H5_HAVE_THREADSAFE && !H5_HAVE_WIN_THREADS*/
+int
+main(void)
+{
+    errx(EXIT_FAILURE, "not implemented in this configuration.");
+}
+
+#endif /*H5_HAVE_THREADSAFE && !H5_HAVE_WIN_THREADS*/
+