#include "run-command.h"
/*
- * Generic implementation of background process infrastructure.
- * See: Documentation/technical/api-sub-process.txt
+ * The sub-process API makes it possible to run background sub-processes
+ * for the entire lifetime of a Git invocation. If Git needs to communicate
+ * with an external process multiple times, then this can reduces the process
+ * invocation overhead. Git and the sub-process communicate through stdin and
+ * stdout.
+ *
+ * The sub-processes are kept in a hashmap by command name and looked up
+ * via the subprocess_find_entry function. If an existing instance can not
+ * be found then a new process should be created and started. When the
+ * parent git command terminates, all sub-processes are also terminated.
+ *
+ * This API is based on the run-command API.
*/
/* data structures */
+/* Members should not be accessed directly. */
struct subprocess_entry {
struct hashmap_entry ent; /* must be the first member! */
const char *cmd;
struct child_process process;
};
+struct subprocess_capability {
+ const char *name;
+
+ /*
+ * subprocess_handshake will "|=" this value to supported_capabilities
+ * if the server reports that it supports this capability.
+ */
+ unsigned int flag;
+};
+
/* subprocess functions */
+/* Function to test two subprocess hashmap entries for equality. */
extern int cmd2process_cmp(const void *unused_cmp_data,
const struct subprocess_entry *e1,
const struct subprocess_entry *e2,
const void *unused_keydata);
+/*
+ * User-supplied function to initialize the sub-process. This is
+ * typically used to negotiate the interface version and capabilities.
+ */
typedef int(*subprocess_start_fn)(struct subprocess_entry *entry);
+
+/* Start a subprocess and add it to the subprocess hashmap. */
int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
subprocess_start_fn startfn);
+/* Kill a subprocess and remove it from the subprocess hashmap. */
void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry);
+/* Find a subprocess in the subprocess hashmap. */
struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd);
/* subprocess helper functions */
+/* Get the underlying `struct child_process` from a subprocess. */
static inline struct child_process *subprocess_get_child_process(
struct subprocess_entry *entry)
{
return &entry->process;
}
+/*
+ * Perform the version and capability negotiation as described in the "Long
+ * Running Filter Process" section of the gitattributes documentation using the
+ * given requested versions and capabilities. The "versions" and "capabilities"
+ * parameters are arrays terminated by a 0 or blank struct.
+ *
+ * This function is typically called when a subprocess is started (as part of
+ * the "startfn" passed to subprocess_start).
+ */
+int subprocess_handshake(struct subprocess_entry *entry,
+ const char *welcome_prefix,
+ int *versions,
+ int *chosen_version,
+ struct subprocess_capability *capabilities,
+ unsigned int *supported_capabilities);
+
/*
* Helper function that will read packets looking for "status=<foo>"
* key/value pairs and return the value from the last "status" packet