1 files changed, 184 insertions, 0 deletions
diff --git a/include/git2/sys/commit_graph.h b/include/git2/sys/commit_graph.h
new file mode 100644
index 0000000..06e045f
--- /dev/null
+++ b/include/git2/sys/commit_graph.h
@@ -0,0 +1,184 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_sys_git_commit_graph_h__
+#define INCLUDE_sys_git_commit_graph_h__
+
+#include "git2/common.h"
+#include "git2/types.h"
+
+/**
+ * @file git2/sys/commit_graph.h
+ * @brief Git commit-graph
+ * @defgroup git_commit_graph Git commit-graph APIs
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * Opens a `git_commit_graph` from a path to an objects directory.
+ *
+ * This finds, opens, and validates the `commit-graph` file.
+ *
+ * @param cgraph_out the `git_commit_graph` struct to initialize.
+ * @param objects_dir the path to a git objects directory.
+ * @return Zero on success; -1 on failure.
+ */
+GIT_EXTERN(int) git_commit_graph_open(
+	git_commit_graph **cgraph_out,
+	const char *objects_dir
+#ifdef GIT_EXPERIMENTAL_SHA256
+	, git_oid_t oid_type
+#endif
+	);
+
+/**
+ * Frees commit-graph data. This should only be called when memory allocated
+ * using `git_commit_graph_open` is not returned to libgit2 because it was not
+ * associated with the ODB through a successful call to
+ * `git_odb_set_commit_graph`.
+ *
+ * @param cgraph the commit-graph object to free. If NULL, no action is taken.
+ */
+GIT_EXTERN(void) git_commit_graph_free(git_commit_graph *cgraph);
+
+/**
+ * Create a new writer for `commit-graph` files.
+ *
+ * @param out Location to store the writer pointer.
+ * @param objects_info_dir The `objects/info` directory.
+ * The `commit-graph` file will be written in this directory.
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_commit_graph_writer_new(
+		git_commit_graph_writer **out,
+		const char *objects_info_dir
+#ifdef GIT_EXPERIMENTAL_SHA256
+	, git_oid_t oid_type
+#endif
+		);
+
+/**
+ * Free the commit-graph writer and its resources.
+ *
+ * @param w The writer to free. If NULL no action is taken.
+ */
+GIT_EXTERN(void) git_commit_graph_writer_free(git_commit_graph_writer *w);
+
+/**
+ * Add an `.idx` file (associated to a packfile) to the writer.
+ *
+ * @param w The writer.
+ * @param repo The repository that owns the `.idx` file.
+ * @param idx_path The path of an `.idx` file.
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_commit_graph_writer_add_index_file(
+		git_commit_graph_writer *w,
+		git_repository *repo,
+		const char *idx_path);
+
+/**
+ * Add a revwalk to the writer. This will add all the commits from the revwalk
+ * to the commit-graph.
+ *
+ * @param w The writer.
+ * @param walk The git_revwalk.
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_commit_graph_writer_add_revwalk(
+		git_commit_graph_writer *w,
+		git_revwalk *walk);
+
+
+/**
+ * The strategy to use when adding a new set of commits to a pre-existing
+ * commit-graph chain.
+ */
+typedef enum {
+	/**
+	 * Do not split commit-graph files. The other split strategy-related option
+	 * fields are ignored.
+	 */
+	GIT_COMMIT_GRAPH_SPLIT_STRATEGY_SINGLE_FILE = 0
+} git_commit_graph_split_strategy_t;
+
+/**
+ * Options structure for
+ * `git_commit_graph_writer_commit`/`git_commit_graph_writer_dump`.
+ *
+ * Initialize with `GIT_COMMIT_GRAPH_WRITER_OPTIONS_INIT`. Alternatively, you
+ * can use `git_commit_graph_writer_options_init`.
+ */
+typedef struct {
+	unsigned int version;
+
+	/**
+	 * The strategy to use when adding new commits to a pre-existing commit-graph
+	 * chain.
+	 */
+	git_commit_graph_split_strategy_t split_strategy;
+
+	/**
+	 * The number of commits in level N is less than X times the number of
+	 * commits in level N + 1. Default is 2.
+	 */
+	float size_multiple;
+
+	/**
+	 * The number of commits in level N + 1 is more than C commits.
+	 * Default is 64000.
+	 */
+	size_t max_commits;
+} git_commit_graph_writer_options;
+
+#define GIT_COMMIT_GRAPH_WRITER_OPTIONS_VERSION 1
+#define GIT_COMMIT_GRAPH_WRITER_OPTIONS_INIT { \
+		GIT_COMMIT_GRAPH_WRITER_OPTIONS_VERSION \
+	}
+
+/**
+ * Initialize git_commit_graph_writer_options structure
+ *
+ * Initializes a `git_commit_graph_writer_options` with default values. Equivalent to
+ * creating an instance with `GIT_COMMIT_GRAPH_WRITER_OPTIONS_INIT`.
+ *
+ * @param opts The `git_commit_graph_writer_options` struct to initialize.
+ * @param version The struct version; pass `GIT_COMMIT_GRAPH_WRITER_OPTIONS_VERSION`.
+ * @return Zero on success; -1 on failure.
+ */
+GIT_EXTERN(int) git_commit_graph_writer_options_init(
+	git_commit_graph_writer_options *opts,
+	unsigned int version);
+
+/**
+ * Write a `commit-graph` file to a file.
+ *
+ * @param w The writer
+ * @param opts Pointer to git_commit_graph_writer_options struct.
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_commit_graph_writer_commit(
+		git_commit_graph_writer *w,
+		git_commit_graph_writer_options *opts);
+
+/**
+ * Dump the contents of the `commit-graph` to an in-memory buffer.
+ *
+ * @param buffer Buffer where to store the contents of the `commit-graph`.
+ * @param w The writer.
+ * @param opts Pointer to git_commit_graph_writer_options struct.
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_commit_graph_writer_dump(
+		git_buf *buffer,
+		git_commit_graph_writer *w,
+		git_commit_graph_writer_options *opts);
+
+/** @} */
+GIT_END_DECL
+#endif