git/sub-process.h
Elijah Newren f332121e75 treewide: remove unnecessary git-compat-util.h includes in headers
For sanity, we should probably do one of the following:

(a) make C and header files both depend upon everything they need
(b) consistently exclude git-compat-util.h from headers and require it
    be the first include in C files

Currently, we have some of the headers following (a) and others
following (b), which makes things messy.  In the past I was pushed
towards (b), as per [1] and [2].  Further, during this series I
discovered that this mixture empirically will mean that we end up with C
files that do not directly include git-compat-util.h, and do include
headers that don't include git-compat-util.h, with the result that we
likely have headers included before an indirect inclusion of
git-compat-util.h.  Since git-compat-util.h has tricky platform-specific
stuff that is meant to be included before everything else, this state of
affairs is risky and may lead to things breaking in subtle ways (and
only on some platforms) as per [1] and [2].

Since including git-compat-util.h in existing header files makes it
harder for us to catch C files that are missing that include, let's
switch to (b) to make the enforcement of this rule easier.  Remove the
inclusion of git-compat-util.h from header files other than the ones
that have been approved as alternate first includes.

[1] https://lore.kernel.org/git/20180811173406.GA9119@sigill.intra.peff.net/
[2] https://lore.kernel.org/git/20180811174301.GA9287@sigill.intra.peff.net/

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-02-23 17:25:28 -08:00

98 lines
3.1 KiB
C

#ifndef SUBPROCESS_H
#define SUBPROCESS_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;
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. */
int cmd2process_cmp(const void *unused_cmp_data,
const struct hashmap_entry *e,
const struct hashmap_entry *entry_or_key,
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