moving files to /server to make merge possible

server/core/buffer.c

@@ -0,0 +1,207 @@
+/*
+ * This file is distributed as part of the SkySQL Gateway.  It 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,
+ * version 2.
+ *
+ * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Copyright SkySQL Ab 2013
+ */
+
+/**
+ * @file buffer.h  - The Gateway buffer management functions
+ *
+ * The buffer management is based on the principle of a linked list
+ * of variable size buffer, the intention beign to allow longer
+ * content to be buffered in a list and minimise any need to copy
+ * data between buffers.
+ *
+ * @verbatim
+ * Revision History
+ *
+ * Date		Who			Description
+ * 10/06/13	Mark Riddoch		Initial implementation
+ * 11/07/13	Mark Riddoch		Add reference count mechanism
+ * 16/07/2013	Massimiliano Pinto	Added command type to gwbuf struct
+ *
+ * @endverbatim
+ */
+#include <stdlib.h>
+#include <buffer.h>
+#include <atomic.h>
+
+
+/**
+ * Allocate a new gateway buffer structure of size bytes.
+ *
+ * For now we allocate memory directly from malloc for buffer the management
+ * structure and the actual data buffer itself. We may swap at a future date
+ * to a more effecient mechanism.
+ *
+ * @param	size The size in bytes of the data area required
+ * @return	Pointer to the buffer structure or NULL if memory could not
+ *		be allocated.
+ */
+GWBUF	*
+gwbuf_alloc(unsigned int size)
+{
+GWBUF		*rval;
+SHARED_BUF	*sbuf;
+
+	// Allocate the buffer header
+	if ((rval = (GWBUF *)malloc(sizeof(GWBUF))) == NULL)
+	{
+		return NULL;
+	}
+
+	// Allocate the shared data buffer
+	if ((sbuf = (SHARED_BUF *)malloc(sizeof(SHARED_BUF))) == NULL)
+	{
+		free(rval);
+		return NULL;
+	}
+
+	// Allocate the space for the actual data
+	if ((sbuf->data = (unsigned char *)malloc(size)) == NULL)
+	{
+		free(rval);
+		free(sbuf);
+		return NULL;
+	}
+	rval->start = sbuf->data;
+	rval->end = rval->start + size;
+	sbuf->refcount = 1;
+	rval->sbuf = sbuf;
+	rval->next = NULL;
+	rval->command = 0;
+
+	return rval;
+}
+
+/**
+ * Free a gateway buffer
+ *
+ * @param buf The buffer to free
+ */
+void
+gwbuf_free(GWBUF *buf)
+{
+	atomic_add(&buf->sbuf->refcount, -1);
+	if (buf->sbuf->refcount == 0)
+	{
+		free(buf->sbuf->data);
+		free(buf->sbuf);
+	}
+	free(buf);
+}
+
+/**
+ * Increment the usage count of a gateway buffer. This gets a new
+ * GWBUF structure that shares the actual data with the existing
+ * GWBUF structure but allows for the data copy to be avoided and
+ * also for each GWBUF to point to different portions of the same
+ * SHARED_BUF.
+ *
+ * @param buf The buffer to use
+ * @return A new GWBUF structure
+ */
+GWBUF *
+gwbuf_clone(GWBUF *buf)
+{
+GWBUF	*rval;
+
+	if ((rval = (GWBUF *)malloc(sizeof(GWBUF))) == NULL)
+	{
+		return NULL;
+	}
+
+	atomic_add(&buf->sbuf->refcount, 1);
+	rval->sbuf = buf->sbuf;
+	rval->start = buf->start;
+	rval->end = buf->end;
+	rval->next = NULL;
+	rval->command = buf->command;
+
+	return rval;
+}
+/**
+ * Append a buffer onto a linked list of buffer structures.
+ *
+ * This call should be made with the caller holding the lock for the linked
+ * list.
+ *
+ * @param head	The current head of the linked list
+ * @param tail	The new buffer to make the tail of the linked list
+ * @return	The new head of the linked list
+ */
+GWBUF	*
+gwbuf_append(GWBUF *head, GWBUF *tail)
+{
+GWBUF	*ptr = head;
+
+	if (!head)
+		return tail;
+	while (ptr->next)
+	{
+		ptr = ptr->next;
+	}
+	ptr->next = tail;
+	return head;
+}
+
+/**
+ * Consume data from a buffer in the linked list. The assumption is to consume
+ * n bytes from the buffer chain.
+ *
+ * If after consuming the bytes from the first buffer that buffer becomes
+ * empty it will be freed and the linked list updated.
+ *
+ * The return value is the new head of the linked list.
+ *
+ * This call should be made with the caller holding the lock for the linked
+ * list.
+ *
+ * @param head		The head of the linked list
+ * @param length	The amount of data to consume
+ * @return The head of the linked list
+ */
+GWBUF *
+gwbuf_consume(GWBUF *head, unsigned int length)
+{
+GWBUF *rval = head;
+
+	GWBUF_CONSUME(head, length);
+	if (GWBUF_EMPTY(head))
+	{
+		rval = head->next;
+		gwbuf_free(head);
+	}
+	return rval;
+}
+
+/**
+ * Return the number of bytes of data in the linked list.
+ *
+ * @param head	The current head of the linked list
+ * @return The number of bytes of data in the linked list
+ */
+unsigned int
+gwbuf_length(GWBUF *head)
+{
+int	rval = 0;
+
+	while (head)
+	{
+		rval += GWBUF_LENGTH(head);
+		head = head->next;
+	}
+	return rval;
+}