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-rw-r--r--src/lib/cbuff.c145
1 files changed, 145 insertions, 0 deletions
diff --git a/src/lib/cbuff.c b/src/lib/cbuff.c
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+++ b/src/lib/cbuff.c
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+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+/**
+ * @file cbuff.c
+ * @brief Implementation of a ring buffer
+ *
+ * @copyright 2013 The FreeRADIUS server project
+ * @copyright 2013 Arran Cudbard-Bell <a.cudbardb@freeradius.org>
+ */
+RCSID("$Id$")
+
+#include <freeradius-devel/libradius.h>
+
+#ifdef HAVE_PTHREAD_H
+# define PTHREAD_MUTEX_LOCK(_x) if (_x->lock) pthread_mutex_lock(&((_x)->mutex))
+# define PTHREAD_MUTEX_UNLOCK(_x) if (_x->lock) pthread_mutex_unlock(&((_x)->mutex))
+#else
+# define PTHREAD_MUTEX_LOCK(_x)
+# define PTHREAD_MUTEX_UNLOCK(_x)
+#endif
+
+/** Standard thread safe circular buffer
+ *
+ */
+struct fr_cbuff {
+ void const *end; //!< End of allocated memory
+
+ uint32_t size;
+ uint32_t in; //!< Write index
+ uint32_t out; //!< Read index
+
+ void **elem; //!< Ring buffer data
+
+ bool lock; //!< Perform thread synchronisation
+ pthread_mutex_t mutex; //!< Thread synchronisation mutex
+};
+
+/** Initialise a new circular buffer
+ *
+ * @param ctx to allocate the buffer in.
+ * @param size of buffer to allocate.
+ * @param lock If true, insert and next operations will lock the buffer.
+ * @return new cbuff, or NULL on error.
+ */
+#ifdef HAVE_PTHREAD_H
+fr_cbuff_t *fr_cbuff_alloc(TALLOC_CTX *ctx, uint32_t size, bool lock)
+#else
+fr_cbuff_t *fr_cbuff_alloc(TALLOC_CTX *ctx, uint32_t size, UNUSED bool lock)
+#endif
+{
+ fr_cbuff_t *cbuff;
+
+ uint32_t pow;
+
+ /*
+ * Find the nearest power of 2 (rounding up)
+ */
+ for (pow = 0x00000001;
+ pow < size;
+ pow <<= 1);
+ size = pow;
+ size--;
+
+ cbuff = talloc_zero(ctx, fr_cbuff_t);
+ if (!cbuff) {
+ return NULL;
+ }
+ cbuff->elem = talloc_zero_array(cbuff, void *, size);
+ if (!cbuff->elem) {
+ return NULL;
+ }
+ cbuff->size = size;
+
+#ifdef HAVE_PTHREAD_H
+ if (lock) {
+ cbuff->lock = true;
+ pthread_mutex_init(&cbuff->mutex, NULL);
+ }
+#endif
+ return cbuff;
+}
+
+/** Insert a new element into the buffer, and steal it from it's original context
+ *
+ * cbuff will steal obj and insert it into it's own context.
+ *
+ * @param cbuff to insert element into
+ * @param obj to insert, must of been allocated with talloc
+ */
+void fr_cbuff_rp_insert(fr_cbuff_t *cbuff, void *obj)
+{
+ PTHREAD_MUTEX_LOCK(cbuff);
+
+ if (cbuff->elem[cbuff->in]) {
+ TALLOC_FREE(cbuff->elem[cbuff->in]);
+ }
+
+ cbuff->elem[cbuff->in] = talloc_steal(cbuff, obj);
+
+ cbuff->in = (cbuff->in + 1) & cbuff->size;
+
+ /* overwrite - out is advanced ahead of in */
+ if (cbuff->in == cbuff->out) {
+ cbuff->out = (cbuff->out + 1) & cbuff->size;
+ }
+
+ PTHREAD_MUTEX_UNLOCK(cbuff);
+}
+
+/** Remove an item from the buffer, and reparent to ctx
+ *
+ * @param cbuff to remove element from
+ * @param ctx to hang obj off.
+ * @return NULL if no elements in the buffer, else an element from the buffer reparented to ctx.
+ */
+void *fr_cbuff_rp_next(fr_cbuff_t *cbuff, TALLOC_CTX *ctx)
+{
+ void *obj = NULL;
+
+ PTHREAD_MUTEX_LOCK(cbuff);
+
+ /* Buffer is empty */
+ if (cbuff->out == cbuff->in) goto done;
+
+ obj = talloc_steal(ctx, cbuff->elem[cbuff->out]);
+ cbuff->out = (cbuff->out + 1) & cbuff->size;
+
+done:
+ PTHREAD_MUTEX_UNLOCK(cbuff);
+ return obj;
+}