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1 | #ifndef SUBPROCESS_H | |
2 | #define SUBPROCESS_H | |
3 | ||
4 | #include "git-compat-util.h" | |
5 | #include "hashmap.h" | |
6 | #include "run-command.h" | |
7 | ||
8 | /* | |
9 | * The sub-process API makes it possible to run background sub-processes | |
10 | * for the entire lifetime of a Git invocation. If Git needs to communicate | |
11 | * with an external process multiple times, then this can reduces the process | |
12 | * invocation overhead. Git and the sub-process communicate through stdin and | |
13 | * stdout. | |
14 | * | |
15 | * The sub-processes are kept in a hashmap by command name and looked up | |
16 | * via the subprocess_find_entry function. If an existing instance can not | |
17 | * be found then a new process should be created and started. When the | |
18 | * parent git command terminates, all sub-processes are also terminated. | |
19 | * | |
20 | * This API is based on the run-command API. | |
21 | */ | |
22 | ||
23 | /* data structures */ | |
24 | ||
25 | /* Members should not be accessed directly. */ | |
26 | struct subprocess_entry { | |
27 | struct hashmap_entry ent; /* must be the first member! */ | |
28 | const char *cmd; | |
29 | struct child_process process; | |
30 | }; | |
31 | ||
32 | struct subprocess_capability { | |
33 | const char *name; | |
34 | ||
35 | /* | |
36 | * subprocess_handshake will "|=" this value to supported_capabilities | |
37 | * if the server reports that it supports this capability. | |
38 | */ | |
39 | unsigned int flag; | |
40 | }; | |
41 | ||
42 | /* subprocess functions */ | |
43 | ||
44 | /* Function to test two subprocess hashmap entries for equality. */ | |
45 | extern int cmd2process_cmp(const void *unused_cmp_data, | |
46 | const void *e1, | |
47 | const void *e2, | |
48 | const void *unused_keydata); | |
49 | ||
50 | /* | |
51 | * User-supplied function to initialize the sub-process. This is | |
52 | * typically used to negotiate the interface version and capabilities. | |
53 | */ | |
54 | typedef int(*subprocess_start_fn)(struct subprocess_entry *entry); | |
55 | ||
56 | /* Start a subprocess and add it to the subprocess hashmap. */ | |
57 | int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd, | |
58 | subprocess_start_fn startfn); | |
59 | ||
60 | /* Kill a subprocess and remove it from the subprocess hashmap. */ | |
61 | void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry); | |
62 | ||
63 | /* Find a subprocess in the subprocess hashmap. */ | |
64 | struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd); | |
65 | ||
66 | /* subprocess helper functions */ | |
67 | ||
68 | /* Get the underlying `struct child_process` from a subprocess. */ | |
69 | static inline struct child_process *subprocess_get_child_process( | |
70 | struct subprocess_entry *entry) | |
71 | { | |
72 | return &entry->process; | |
73 | } | |
74 | ||
75 | /* | |
76 | * Perform the version and capability negotiation as described in the | |
77 | * "Handshake" section of long-running-process-protocol.txt using the | |
78 | * given requested versions and capabilities. The "versions" and "capabilities" | |
79 | * parameters are arrays terminated by a 0 or blank struct. | |
80 | * | |
81 | * This function is typically called when a subprocess is started (as part of | |
82 | * the "startfn" passed to subprocess_start). | |
83 | */ | |
84 | int subprocess_handshake(struct subprocess_entry *entry, | |
85 | const char *welcome_prefix, | |
86 | int *versions, | |
87 | int *chosen_version, | |
88 | struct subprocess_capability *capabilities, | |
89 | unsigned int *supported_capabilities); | |
90 | ||
91 | /* | |
92 | * Helper function that will read packets looking for "status=<foo>" | |
93 | * key/value pairs and return the value from the last "status" packet | |
94 | */ | |
95 | ||
96 | int subprocess_read_status(int fd, struct strbuf *status); | |
97 | ||
98 | #endif |