freshlybakedca.ke
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1#ifndef SUBPROCESS_H
2#define SUBPROCESS_H
3
4#include "hashmap.h"
5#include "run-command.h"
6
7/*
8 * The sub-process API makes it possible to run background sub-processes
9 * for the entire lifetime of a Git invocation. If Git needs to communicate
10 * with an external process multiple times, then this can reduces the process
11 * invocation overhead. Git and the sub-process communicate through stdin and
12 * stdout.
13 *
14 * The sub-processes are kept in a hashmap by command name and looked up
15 * via the subprocess_find_entry function. If an existing instance can not
16 * be found then a new process should be created and started. When the
17 * parent git command terminates, all sub-processes are also terminated.
18 *
19 * This API is based on the run-command API.
20 */
21
22 /* data structures */
23
24/* Members should not be accessed directly. */
25struct subprocess_entry {
26 struct hashmap_entry ent;
27 const char *cmd;
28 struct child_process process;
29};
30
31struct subprocess_capability {
32 const char *name;
33
34 /*
35 * subprocess_handshake will "|=" this value to supported_capabilities
36 * if the server reports that it supports this capability.
37 */
38 unsigned int flag;
39};
40
41/* subprocess functions */
42
43/* Function to test two subprocess hashmap entries for equality. */
44int cmd2process_cmp(const void *unused_cmp_data,
45 const struct hashmap_entry *e,
46 const struct hashmap_entry *entry_or_key,
47 const void *unused_keydata);
48
49/*
50 * User-supplied function to initialize the sub-process. This is
51 * typically used to negotiate the interface version and capabilities.
52 */
53typedef int(*subprocess_start_fn)(struct subprocess_entry *entry);
54
55/* Start a subprocess and add it to the subprocess hashmap. */
56int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
57 subprocess_start_fn startfn);
58
59/* Kill a subprocess and remove it from the subprocess hashmap. */
60void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry);
61
62/* Find a subprocess in the subprocess hashmap. */
63struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd);
64
65/* subprocess helper functions */
66
67/* Get the underlying `struct child_process` from a subprocess. */
68static inline struct child_process *subprocess_get_child_process(
69 struct subprocess_entry *entry)
70{
71 return &entry->process;
72}
73
74/*
75 * Perform the version and capability negotiation as described in the
76 * "Handshake" section of long-running-process-protocol.adoc using the
77 * given requested versions and capabilities. The "versions" and "capabilities"
78 * parameters are arrays terminated by a 0 or blank struct.
79 *
80 * This function is typically called when a subprocess is started (as part of
81 * the "startfn" passed to subprocess_start).
82 */
83int subprocess_handshake(struct subprocess_entry *entry,
84 const char *welcome_prefix,
85 int *versions,
86 int *chosen_version,
87 struct subprocess_capability *capabilities,
88 unsigned int *supported_capabilities);
89
90/*
91 * Helper function that will read packets looking for "status=<foo>"
92 * key/value pairs and return the value from the last "status" packet
93 */
94
95int subprocess_read_status(int fd, struct strbuf *status);
96
97#endif