Show changes to 5 files +212 −103
Documentation/technical/api-sub-process.txt, Makefile, convert.c, sub-process.c, sub-process.h
diff --git a/Documentation/technical/api-sub-process.txt b/Documentation/technical/api-sub-process.txt
new file mode 100644
index 0000000000..793508cf3e
--- /dev/null
+++ b/Documentation/technical/api-sub-process.txt
@@ -0,0 +1,59 @@
+sub-process API
+===============
+
+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
+---------------
+
+* `struct subprocess_entry`
+
+The sub-process structure. Members should not be accessed directly.
+
+Types
+-----
+
+'int(*subprocess_start_fn)(struct subprocess_entry *entry)'::
+
+ User-supplied function to initialize the sub-process. This is
+ typically used to negotiate the interface version and capabilities.
+
+
+Functions
+---------
+
+`cmd2process_cmp`::
+
+ Function to test two subprocess hashmap entries for equality.
+
+`subprocess_start`::
+
+ Start a subprocess and add it to the subprocess hashmap.
+
+`subprocess_stop`::
+
+ Kill a subprocess and remove it from the subprocess hashmap.
+
+`subprocess_find_entry`::
+
+ Find a subprocess in the subprocess hashmap.
+
+`subprocess_get_child_process`::
+
+ Get the underlying `struct child_process` from a subprocess.
+
+`subprocess_read_status`::
+
+ Helper function to read packets looking for the last "status=<foo>"
+ key/value pair.
diff --git a/Makefile b/Makefile
index eb1a1a7cff..97c87fb647 100644
--- a/Makefile
+++ b/Makefile
@@ -840,6 +840,7 @@ LIB_OBJS += streaming.o
LIB_OBJS += string-list.o
LIB_OBJS += submodule.o
LIB_OBJS += submodule-config.o
+LIB_OBJS += sub-process.o
LIB_OBJS += symlinks.o
LIB_OBJS += tag.o
LIB_OBJS += tempfile.o
diff --git a/convert.c b/convert.c
index cfae45aeee..79d04907a5 100644
--- a/convert.c
+++ b/convert.c
@@ -4,6 +4,7 @@
#include "quote.h"
#include "sigchain.h"
#include "pkt-line.h"
+#include "sub-process.h"
/*
* convert.c - convert a file when checking it out and checking it in.
@@ -496,12 +497,6 @@ static int apply_single_file_filter(const char *path, const char *src, size_t le
#define CAP_CLEAN (1u<<0)
#define CAP_SMUDGE (1u<<1)
-struct subprocess_entry {
- struct hashmap_entry ent; /* must be the first member! */
- const char *cmd;
- struct child_process process;
-};
-
struct cmd2process {
struct subprocess_entry subprocess; /* must be the first member! */
unsigned int supported_capabilities;
@@ -510,65 +505,6 @@ struct cmd2process {
static int subprocess_map_initialized;
static struct hashmap subprocess_map;
-static int cmd2process_cmp(const struct subprocess_entry *e1,
- const struct subprocess_entry *e2,
- const void *unused)
-{
- return strcmp(e1->cmd, e2->cmd);
-}
-
-static struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd)
-{
- struct subprocess_entry key;
-
- hashmap_entry_init(&key, strhash(cmd));
- key.cmd = cmd;
- return hashmap_get(hashmap, &key, NULL);
-}
-
-static void subprocess_read_status(int fd, struct strbuf *status)
-{
- struct strbuf **pair;
- char *line;
- for (;;) {
- line = packet_read_line(fd, NULL);
- if (!line)
- break;
- pair = strbuf_split_str(line, '=', 2);
- if (pair[0] && pair[0]->len && pair[1]) {
- /* the last "status=<foo>" line wins */
- if (!strcmp(pair[0]->buf, "status=")) {
- strbuf_reset(status);
- strbuf_addbuf(status, pair[1]);
- }
- }
- strbuf_list_free(pair);
- }
-}
-
-static void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry)
-{
- if (!entry)
- return;
-
- entry->process.clean_on_exit = 0;
- kill(entry->process.pid, SIGTERM);
- finish_command(&entry->process);
-
- hashmap_remove(hashmap, entry, NULL);
-}
-
-static void subprocess_exit_handler(struct child_process *process)
-{
- sigchain_push(SIGPIPE, SIG_IGN);
- /* Closing the pipe signals the subprocess to initiate a shutdown. */
- close(process->in);
- close(process->out);
- sigchain_pop(SIGPIPE);
- /* Finish command will wait until the shutdown is complete. */
- finish_command(process);
-}
-
static int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
{
int err;
@@ -629,44 +565,6 @@ static int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
return err;
}
-typedef int(*subprocess_start_fn)(struct subprocess_entry *entry);
-int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
- subprocess_start_fn startfn)
-{
- int err;
- struct child_process *process;
- const char *argv[] = { cmd, NULL };
-
- entry->cmd = cmd;
- process = &entry->process;
-
- child_process_init(process);
- process->argv = argv;
- process->use_shell = 1;
- process->in = -1;
- process->out = -1;
- process->clean_on_exit = 1;
- process->clean_on_exit_handler = subprocess_exit_handler;
-
- err = start_command(process);
- if (err) {
- error("cannot fork to run subprocess '%s'", cmd);
- return err;
- }
-
- hashmap_entry_init(entry, strhash(cmd));
-
- err = startfn(entry);
- if (err) {
- error("initialization for subprocess '%s' failed", cmd);
- subprocess_stop(hashmap, entry);
- return err;
- }
-
- hashmap_add(hashmap, entry);
- return 0;
-}
-
static int apply_multi_file_filter(const char *path, const char *src, size_t len,
int fd, struct strbuf *dst, const char *cmd,
const unsigned int wanted_capability)
diff --git a/sub-process.c b/sub-process.c
new file mode 100644
index 0000000000..536b60cced
--- /dev/null
+++ b/sub-process.c
@@ -0,0 +1,102 @@
+/*
+ * Generic implementation of background process infrastructure.
+ */
+#include "sub-process.h"
+#include "sigchain.h"
+#include "pkt-line.h"
+
+int cmd2process_cmp(const struct subprocess_entry *e1,
+ const struct subprocess_entry *e2,
+ const void *unused)
+{
+ return strcmp(e1->cmd, e2->cmd);
+}
+
+struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd)
+{
+ struct subprocess_entry key;
+
+ hashmap_entry_init(&key, strhash(cmd));
+ key.cmd = cmd;
+ return hashmap_get(hashmap, &key, NULL);
+}
+
+void subprocess_read_status(int fd, struct strbuf *status)
+{
+ struct strbuf **pair;
+ char *line;
+ for (;;) {
+ line = packet_read_line(fd, NULL);
+ if (!line)
+ break;
+ pair = strbuf_split_str(line, '=', 2);
+ if (pair[0] && pair[0]->len && pair[1]) {
+ /* the last "status=<foo>" line wins */
+ if (!strcmp(pair[0]->buf, "status=")) {
+ strbuf_reset(status);
+ strbuf_addbuf(status, pair[1]);
+ }
+ }
+ strbuf_list_free(pair);
+ }
+}
+
+void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry)
+{
+ if (!entry)
+ return;
+
+ entry->process.clean_on_exit = 0;
+ kill(entry->process.pid, SIGTERM);
+ finish_command(&entry->process);
+
+ hashmap_remove(hashmap, entry, NULL);
+}
+
+static void subprocess_exit_handler(struct child_process *process)
+{
+ sigchain_push(SIGPIPE, SIG_IGN);
+ /* Closing the pipe signals the subprocess to initiate a shutdown. */
+ close(process->in);
+ close(process->out);
+ sigchain_pop(SIGPIPE);
+ /* Finish command will wait until the shutdown is complete. */
+ finish_command(process);
+}
+
+int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
+ subprocess_start_fn startfn)
+{
+ int err;
+ struct child_process *process;
+ const char *argv[] = { cmd, NULL };
+
+ entry->cmd = cmd;
+ process = &entry->process;
+
+ child_process_init(process);
+ process->argv = argv;
+ process->use_shell = 1;
+ process->in = -1;
+ process->out = -1;
+ process->clean_on_exit = 1;
+ process->clean_on_exit_handler = subprocess_exit_handler;
+
+ err = start_command(process);
+ if (err) {
+ error("cannot fork to run subprocess '%s'", cmd);
+ return err;
+ }
+
+ hashmap_entry_init(entry, strhash(cmd));
+
+ err = startfn(entry);
+ if (err) {
+ error("initialization for subprocess '%s' failed", cmd);
+ subprocess_stop(hashmap, entry);
+ return err;
+ }
+
+ hashmap_add(hashmap, entry);
+ return 0;
+}
diff --git a/sub-process.h b/sub-process.h
new file mode 100644
index 0000000000..a88e782bfc
--- /dev/null
+++ b/sub-process.h
@@ -0,0 +1,49 @@
+#ifndef SUBPROCESS_H
+#define SUBPROCESS_H
+
+#include "git-compat-util.h"
+#include "hashmap.h"
+#include "run-command.h"
+
+/*
+ * Generic implementation of background process infrastructure.
+ * See Documentation/technical/api-background-process.txt.
+ */
+
+ /* data structures */
+
+struct subprocess_entry {
+ struct hashmap_entry ent; /* must be the first member! */
+ const char *cmd;
+ struct child_process process;
+};
+
+/* subprocess functions */
+
+int cmd2process_cmp(const struct subprocess_entry *e1,
+ const struct subprocess_entry *e2, const void *unused);
+
+typedef int(*subprocess_start_fn)(struct subprocess_entry *entry);
+int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
+ subprocess_start_fn startfn);
+
+void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry);
+
+struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd);
+
+/* subprocess helper functions */
+
+static inline struct child_process *subprocess_get_child_process(
+ struct subprocess_entry *entry)
+{
+ return &entry->process;
+}
+
+/*
+ * Helper function that will read packets looking for "status=<foo>"
+ * key/value pairs and return the value from the last "status" packet
+ */
+
+void subprocess_read_status(int fd, struct strbuf *status);
+
+#endif
Ben Peart