X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Fdynamic-buffer.cpp;fp=src%2Fcommon%2Fdynamic-buffer.cpp;h=945434ca9d6f2fd10fe2f357bdfe61d3a8ae2191;hp=0000000000000000000000000000000000000000;hb=a6bc4ca9d659caf016ef932fcd944029737ac57c;hpb=97535efaa975ca52bf02c2d5e76351bfd2e3defa

diff --git a/src/common/dynamic-buffer.cpp b/src/common/dynamic-buffer.cpp
new file mode 100644
index 000000000..945434ca9
--- /dev/null
+++ b/src/common/dynamic-buffer.cpp
@@ -0,0 +1,192 @@
+/*
+ * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ */
+
+#include <common/dynamic-buffer.h>
+#include <common/buffer-view.h>
+#include <common/utils.h>
+
+/*
+ * Round to (upper) power of two, val is returned if it already is a power of
+ * two.
+ */
+static
+size_t round_to_power_of_2(size_t val)
+{
+	size_t rounded;
+	const int order = utils_get_count_order_u64(val);
+
+	LTTNG_ASSERT(order >= 0);
+	rounded = (1ULL << order);
+	LTTNG_ASSERT(rounded >= val);
+
+	return rounded;
+}
+
+void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer *buffer)
+{
+	LTTNG_ASSERT(buffer);
+	memset(buffer, 0, sizeof(*buffer));
+}
+
+int lttng_dynamic_buffer_append(struct lttng_dynamic_buffer *buffer,
+		const void *buf, size_t len)
+{
+	int ret = 0;
+
+	if (!buffer || (!buf && len)) {
+		ret = -1;
+		goto end;
+	}
+
+	if (len == 0) {
+		/* Not an error, no-op. */
+		goto end;
+	}
+
+	LTTNG_ASSERT(buffer->_capacity >= buffer->size);
+	if (buffer->_capacity < (len + buffer->size)) {
+		ret = lttng_dynamic_buffer_set_capacity(buffer,
+				buffer->_capacity +
+				(len - (buffer->_capacity - buffer->size)));
+		if (ret) {
+			goto end;
+		}
+	}
+
+	memcpy(buffer->data + buffer->size, buf, len);
+	buffer->size += len;
+end:
+	return ret;
+}
+
+int lttng_dynamic_buffer_append_buffer(struct lttng_dynamic_buffer *dst_buffer,
+		const struct lttng_dynamic_buffer *src_buffer)
+{
+	int ret;
+
+	if (!dst_buffer || !src_buffer) {
+		ret = -1;
+		goto end;
+	}
+
+	ret = lttng_dynamic_buffer_append(dst_buffer, src_buffer->data,
+			src_buffer->size);
+end:
+	return ret;
+}
+
+int lttng_dynamic_buffer_append_view(struct lttng_dynamic_buffer *buffer,
+		const struct lttng_buffer_view *src)
+{
+	int ret;
+
+	if (!buffer || !src) {
+		ret = -1;
+		goto end;
+	}
+
+	ret = lttng_dynamic_buffer_append(buffer, src->data,
+			src->size);
+end:
+	return ret;
+}
+
+int lttng_dynamic_buffer_set_size(struct lttng_dynamic_buffer *buffer,
+		size_t new_size)
+{
+	int ret = 0;
+
+	if (!buffer) {
+		goto end;
+	}
+
+	if (new_size == buffer->size) {
+		goto end;
+	}
+
+	if (new_size > buffer->_capacity) {
+		ret = lttng_dynamic_buffer_set_capacity(buffer, new_size);
+		if (ret) {
+			goto end;
+		}
+
+		memset(buffer->data + buffer->size, 0, new_size - buffer->size);
+	} else if (new_size > buffer->size) {
+		memset(buffer->data + buffer->size, 0, new_size - buffer->size);
+	} else {
+		/*
+		 * Shrinking size. There is no need to zero-out the newly
+		 * released memory as it will either be:
+		 *   - overwritten by lttng_dynamic_buffer_append,
+		 *   - expanded later, which will zero-out the memory
+		 *
+		 * Users of external APIs are encouraged to set the buffer's
+		 * size _before_ making such calls.
+		 */
+	}
+
+	buffer->size = new_size;
+end:
+	return ret;
+}
+
+int lttng_dynamic_buffer_set_capacity(struct lttng_dynamic_buffer *buffer,
+		size_t demanded_capacity)
+{
+	int ret = 0;
+	void *new_buf;
+	size_t new_capacity = demanded_capacity ?
+			round_to_power_of_2(demanded_capacity) : 0;
+
+	if (!buffer || demanded_capacity < buffer->size) {
+		/*
+		 * Shrinking a buffer's size by changing its capacity is
+		 * unsupported.
+		 */
+		ret = -1;
+		goto end;
+	}
+
+	if (new_capacity == buffer->_capacity) {
+		goto end;
+	}
+
+	/* Memory is initialized by the size increases. */
+	new_buf = realloc(buffer->data, new_capacity);
+	if (!new_buf) {
+		ret = -1;
+		goto end;
+	}
+
+	buffer->data = (char *) new_buf;
+	buffer->_capacity = new_capacity;
+end:
+	return ret;
+}
+
+/* Release any memory used by the dynamic buffer. */
+void lttng_dynamic_buffer_reset(struct lttng_dynamic_buffer *buffer)
+{
+	if (!buffer) {
+		return;
+	}
+
+	buffer->size = 0;
+	buffer->_capacity = 0;
+	free(buffer->data);
+	buffer->data = NULL;
+}
+
+size_t lttng_dynamic_buffer_get_capacity_left(
+		struct lttng_dynamic_buffer *buffer)
+{
+	if (!buffer) {
+		return 0;
+	}
+
+	return buffer->_capacity - buffer->size;
+}