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Diffstat (limited to 'sub-process.h')
-rw-r--r-- | sub-process.h | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/sub-process.h b/sub-process.h new file mode 100644 index 0000000000..71b18ad5af --- /dev/null +++ b/sub-process.h @@ -0,0 +1,98 @@ +#ifndef SUBPROCESS_H +#define SUBPROCESS_H + +#include "git-compat-util.h" +#include "hashmap.h" +#include "run-command.h" + +/* + * 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 void *e1, + const void *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 + * "Handshake" section of long-running-process-protocol.txt 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 + */ + +int subprocess_read_status(int fd, struct strbuf *status); + +#endif |