common: Add index allocator for error counters

[lttng-tools.git] / src / common / index-allocator.h

diff --git a/src/common/index-allocator.h b/src/common/index-allocator.h
new file mode 100644 (file)
index 0000000..3da733e
--- /dev/null
+++ b/src/common/index-allocator.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#ifndef _COMMON_INDEX_ALLOCATOR_H
+#define _COMMON_INDEX_ALLOCATOR_H
+
+#include <inttypes.h>
+
+struct lttng_index_allocator;
+
+enum lttng_index_allocator_status {
+       LTTNG_INDEX_ALLOCATOR_STATUS_OK,
+       LTTNG_INDEX_ALLOCATOR_STATUS_EMPTY,
+       LTTNG_INDEX_ALLOCATOR_STATUS_ERROR,
+};
+
+/*
+ * Create an index allocator of `index_count` slots.
+ */
+struct lttng_index_allocator *lttng_index_allocator_create(
+               uint64_t index_count);
+
+/*
+ * Get the number of indexes currently in use.
+ */
+uint64_t lttng_index_allocator_get_index_count(
+       struct lttng_index_allocator *allocator);
+
+/*
+ * Allocate (i.e. reserve) a slot.
+ */
+enum lttng_index_allocator_status lttng_index_allocator_alloc(
+               struct lttng_index_allocator *allocator,
+               uint64_t *index);
+
+/*
+ * Release a slot by index. The slot will be re-used by the index allocator
+ * in future 'alloc' calls.
+ */
+enum lttng_index_allocator_status lttng_index_allocator_release(
+               struct lttng_index_allocator *allocator, uint64_t index);
+
+/*
+ * Destroy an index allocator.
+ */
+void lttng_index_allocator_destroy(struct lttng_index_allocator *allocator);
+
+#endif /* _COMMON_INDEX_ALLOCATOR_H */