Thread pool for server

[yaz-moved-to-github.git] / src / tpool.c

diff --git a/src/tpool.c b/src/tpool.c
new file mode 100644 (file)
index 0000000..66d3dff
--- /dev/null
+++ b/src/tpool.c
@@ -0,0 +1,164 @@
+/* This file is part of the YAZ toolkit.
+ * Copyright (C) 1995-2009 Index Data
+ * See the file LICENSE for details.
+ */
+/**
+ * \file 
+ * \brief thread pool workers
+ */
+
+#include <assert.h>
+#include <yaz/nmem.h>
+#include <yaz/tpool.h>
+#include <pthread.h>
+
+struct work_item {
+    void *data;
+    struct work_item *next;
+};
+
+struct yaz_tpool_s {
+    NMEM nmem;
+    pthread_t *thread_id;
+    pthread_mutex_t mutex;
+    pthread_cond_t input_data;
+    int stop_flag;
+    size_t no_threads;
+    struct work_item *input_queue;
+    struct work_item *output_queue;
+    struct work_item *free_queue;
+    void (*work_handler)(void *work_data);
+    void (*work_destroy)(void *work_data);
+};
+
+static struct work_item *queue_remove_last(struct work_item **q)
+{
+    struct work_item **work_p = q, *work_this = 0;
+
+    while (*work_p && (*work_p)->next)
+        work_p = &(*work_p)->next;
+    if (*work_p)
+    {
+        work_this = *work_p;
+        *work_p = 0;
+    }
+    return work_this;
+}
+
+static void queue_trav(struct work_item *q, void (*f)(void *data))
+{
+    for (; q; q = q->next)
+        f(q->data);
+}
+
+void yaz_tpool_add(yaz_tpool_t p, void *data)
+{
+    struct work_item *work_p;
+
+    pthread_mutex_lock(&p->mutex);
+
+    if (p->free_queue)
+    {
+        work_p = p->free_queue;
+        p->free_queue = p->free_queue->next;
+    }
+    else
+        work_p = nmem_malloc(p->nmem, sizeof(*work_p));
+
+    work_p->data = data;
+    work_p->next = p->input_queue;
+    p->input_queue = work_p;
+
+    pthread_cond_signal(&p->input_data);
+    pthread_mutex_unlock(&p->mutex);
+}
+
+void yaz_tpool_destroy(yaz_tpool_t p)
+{
+    if (p)
+    {
+        size_t i;
+
+        pthread_mutex_lock(&p->mutex);
+        p->stop_flag = 1;
+        pthread_cond_broadcast(&p->input_data);
+        pthread_mutex_unlock(&p->mutex);
+        
+        for (i = 0; i < p->no_threads; i++)
+            pthread_join(p->thread_id[i], 0);
+        
+        if (p->work_destroy)
+        {
+            queue_trav(p->input_queue, p->work_destroy);
+            queue_trav(p->output_queue, p->work_destroy);
+        }
+        
+        pthread_cond_destroy(&p->input_data);
+        pthread_mutex_destroy(&p->mutex);
+        nmem_destroy(p->nmem);
+    }
+}
+
+static void *tpool_thread_handler(void *vp)
+{
+    yaz_tpool_t p = (yaz_tpool_t) vp;
+    while (1)
+    {
+        struct work_item *work_this = 0;
+        /* wait for some work */
+        pthread_mutex_lock(&p->mutex);
+        while (!p->stop_flag && !p->input_queue)
+            pthread_cond_wait(&p->input_data, &p->mutex);
+        /* see if we were waken up because we're shutting down */
+        if (p->stop_flag)
+            break;
+        /* got something. Take the last one out of input_queue */
+        assert(p->input_queue);
+        work_this = queue_remove_last(&p->input_queue);
+        assert(work_this);
+
+        pthread_mutex_unlock(&p->mutex);
+
+        /* work on this item */
+        p->work_handler(work_this->data);
+    }        
+    pthread_mutex_unlock(&p->mutex);
+    return 0;
+}
+
+yaz_tpool_t yaz_tpool_create(void (*work_handler)(void *work_data),
+                             void (*work_destroy)(void *work_data),
+                             size_t no_threads)
+{
+    NMEM nmem = nmem_create();
+    yaz_tpool_t p = nmem_malloc(nmem, sizeof(*p));
+    size_t i;
+    p->nmem = nmem;
+    p->stop_flag = 0;
+    p->no_threads = no_threads;
+
+    p->input_queue = 0;
+    p->output_queue = 0;
+    p->free_queue = 0;
+
+    p->work_handler = work_handler;
+    p->work_destroy = work_destroy;
+
+    pthread_mutex_init(&p->mutex, 0);
+    pthread_cond_init(&p->input_data, 0);
+
+    p->thread_id = nmem_malloc(p->nmem, sizeof(*p->thread_id) * p->no_threads);
+    for (i = 0; i < p->no_threads; i++)
+        pthread_create (p->thread_id + i, 0, tpool_thread_handler, p);
+    return p;
+}
+
+/*
+ * Local variables:
+ * c-basic-offset: 4
+ * c-file-style: "Stroustrup"
+ * indent-tabs-mode: nil
+ * End:
+ * vim: shiftwidth=4 tabstop=8 expandtab
+ */
+