git/replace-object.c

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#include "git-compat-util.h"
#include "gettext.h"
#include "hex.h"
#include "oidmap.h"
#include "object-store-ll.h"
#include "replace-object.h"
#include "refs.h"
#include "repository.h"
Fix sparse warnings Fix warnings from 'make check'. - These files don't include 'builtin.h' causing sparse to complain that cmd_* isn't declared: builtin/clone.c:364, builtin/fetch-pack.c:797, builtin/fmt-merge-msg.c:34, builtin/hash-object.c:78, builtin/merge-index.c:69, builtin/merge-recursive.c:22 builtin/merge-tree.c:341, builtin/mktag.c:156, builtin/notes.c:426 builtin/notes.c:822, builtin/pack-redundant.c:596, builtin/pack-refs.c:10, builtin/patch-id.c:60, builtin/patch-id.c:149, builtin/remote.c:1512, builtin/remote-ext.c:240, builtin/remote-fd.c:53, builtin/reset.c:236, builtin/send-pack.c:384, builtin/unpack-file.c:25, builtin/var.c:75 - These files have symbols which should be marked static since they're only file scope: submodule.c:12, diff.c:631, replace_object.c:92, submodule.c:13, submodule.c:14, trace.c:78, transport.c:195, transport-helper.c:79, unpack-trees.c:19, url.c:3, url.c:18, url.c:104, url.c:117, url.c:123, url.c:129, url.c:136, thread-utils.c:21, thread-utils.c:48 - These files redeclare symbols to be different types: builtin/index-pack.c:210, parse-options.c:564, parse-options.c:571, usage.c:49, usage.c:58, usage.c:63, usage.c:72 - These files use a literal integer 0 when they really should use a NULL pointer: daemon.c:663, fast-import.c:2942, imap-send.c:1072, notes-merge.c:362 While we're in the area, clean up some unused #includes in builtin files (mostly exec_cmd.h). Signed-off-by: Stephen Boyd <bebarino@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-03-22 07:51:05 +00:00
#include "commit.h"
static int register_replace_ref(struct repository *r,
const char *refname,
const struct object_id *oid,
int flag UNUSED,
void *cb_data UNUSED)
{
/* Get sha1 from refname */
const char *slash = strrchr(refname, '/');
const char *hash = slash ? slash + 1 : refname;
struct replace_object *repl_obj = xmalloc(sizeof(*repl_obj));
if (get_oid_hex(hash, &repl_obj->original.oid)) {
free(repl_obj);
warning(_("bad replace ref name: %s"), refname);
return 0;
}
/* Copy sha1 from the read ref */
oidcpy(&repl_obj->replacement, oid);
/* Register new object */
if (oidmap_put(r->objects->replace_map, repl_obj))
die(_("duplicate replace ref: %s"), refname);
return 0;
}
void prepare_replace_object(struct repository *r)
{
replace-object: make replace operations thread-safe replace-object functions are very close to being thread-safe: the only current racy section is the lazy initialization at prepare_replace_object(). The following patches will protect some object reading operations to be called threaded, but before that, replace functions must be protected. To do so, add a mutex to struct raw_object_store and acquire it before lazy initializing the replace_map. This won't cause any noticeable performance drop as the mutex will no longer be used after the replace_map is initialized. Later, when the replace functions are called in parallel, thread debuggers might point our use of the added replace_map_initialized flag as a data race. However, as this boolean variable is initialized as false and it's only updated once, there's no real harm. It's perfectly fine if the value is updated right after a thread read it in replace-map.h:lookup_replace_object() (there'll only be a performance penalty for the affected threads at that moment). We could cease the debugger warning protecting the variable reading at the said function. However, this would negatively affect performance for all threads calling it, at any time, so it's not really worthy since the warning doesn't represent a real problem. Instead, to make sure we don't get false positives (at ThreadSanitizer, at least) an entry for the respective function is added to .tsan-suppressions. Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-16 02:39:52 +00:00
if (r->objects->replace_map_initialized)
return;
replace-object: make replace operations thread-safe replace-object functions are very close to being thread-safe: the only current racy section is the lazy initialization at prepare_replace_object(). The following patches will protect some object reading operations to be called threaded, but before that, replace functions must be protected. To do so, add a mutex to struct raw_object_store and acquire it before lazy initializing the replace_map. This won't cause any noticeable performance drop as the mutex will no longer be used after the replace_map is initialized. Later, when the replace functions are called in parallel, thread debuggers might point our use of the added replace_map_initialized flag as a data race. However, as this boolean variable is initialized as false and it's only updated once, there's no real harm. It's perfectly fine if the value is updated right after a thread read it in replace-map.h:lookup_replace_object() (there'll only be a performance penalty for the affected threads at that moment). We could cease the debugger warning protecting the variable reading at the said function. However, this would negatively affect performance for all threads calling it, at any time, so it's not really worthy since the warning doesn't represent a real problem. Instead, to make sure we don't get false positives (at ThreadSanitizer, at least) an entry for the respective function is added to .tsan-suppressions. Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-16 02:39:52 +00:00
pthread_mutex_lock(&r->objects->replace_mutex);
if (r->objects->replace_map_initialized) {
pthread_mutex_unlock(&r->objects->replace_mutex);
return;
}
r->objects->replace_map =
xmalloc(sizeof(*r->objects->replace_map));
oidmap_init(r->objects->replace_map, 0);
for_each_replace_ref(r, register_replace_ref, NULL);
replace-object: make replace operations thread-safe replace-object functions are very close to being thread-safe: the only current racy section is the lazy initialization at prepare_replace_object(). The following patches will protect some object reading operations to be called threaded, but before that, replace functions must be protected. To do so, add a mutex to struct raw_object_store and acquire it before lazy initializing the replace_map. This won't cause any noticeable performance drop as the mutex will no longer be used after the replace_map is initialized. Later, when the replace functions are called in parallel, thread debuggers might point our use of the added replace_map_initialized flag as a data race. However, as this boolean variable is initialized as false and it's only updated once, there's no real harm. It's perfectly fine if the value is updated right after a thread read it in replace-map.h:lookup_replace_object() (there'll only be a performance penalty for the affected threads at that moment). We could cease the debugger warning protecting the variable reading at the said function. However, this would negatively affect performance for all threads calling it, at any time, so it's not really worthy since the warning doesn't represent a real problem. Instead, to make sure we don't get false positives (at ThreadSanitizer, at least) an entry for the respective function is added to .tsan-suppressions. Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-16 02:39:52 +00:00
r->objects->replace_map_initialized = 1;
pthread_mutex_unlock(&r->objects->replace_mutex);
}
/* We allow "recursive" replacement. Only within reason, though */
#define MAXREPLACEDEPTH 5
/*
* If a replacement for object oid has been set up, return the
* replacement object's name (replaced recursively, if necessary).
* The return value is either oid or a pointer to a
* permanently-allocated value. This function always respects replace
repository: create read_replace_refs setting The 'read_replace_refs' global specifies whether or not we should respect the references of the form 'refs/replace/<oid>' to replace which object we look up when asking for '<oid>'. This global has caused issues when it is not initialized properly, such as in b6551feadfd (merge-tree: load default git config, 2023-05-10). To make this more robust, move its config-based initialization out of git_default_config and into prepare_repo_settings(). This provides a repository-scoped version of the 'read_replace_refs' global. The global still has its purpose: it is disabled process-wide by the GIT_NO_REPLACE_OBJECTS environment variable or by a call to disable_replace_refs() in some specific Git commands. Since we already encapsulated the use of the constant inside replace_refs_enabled(), we can perform the initialization inside that method, if necessary. This solves the problem of forgetting to check the config, as we will check it before returning this value. Due to this encapsulation, the global can move to be static within replace-object.c. There is an interesting behavior change possible here: we now have a repository-scoped understanding of this config value. Thus, if there was a command that recurses into submodules and might follow replace refs, then it would now respect the core.useReplaceRefs config value in each repository. 'git grep --recurse-submodules' is such a command that recurses into submodules in-process. We can demonstrate the granularity of this config value via a test in t7814. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-06 13:24:37 +00:00
* references, regardless of the value of r->settings.read_replace_refs.
*/
const struct object_id *do_lookup_replace_object(struct repository *r,
const struct object_id *oid)
{
int depth = MAXREPLACEDEPTH;
const struct object_id *cur = oid;
prepare_replace_object(r);
/* Try to recursively replace the object */
while (depth-- > 0) {
struct replace_object *repl_obj =
oidmap_get(r->objects->replace_map, cur);
if (!repl_obj)
return cur;
cur = &repl_obj->replacement;
}
die(_("replace depth too high for object %s"), oid_to_hex(oid));
}
repository: create read_replace_refs setting The 'read_replace_refs' global specifies whether or not we should respect the references of the form 'refs/replace/<oid>' to replace which object we look up when asking for '<oid>'. This global has caused issues when it is not initialized properly, such as in b6551feadfd (merge-tree: load default git config, 2023-05-10). To make this more robust, move its config-based initialization out of git_default_config and into prepare_repo_settings(). This provides a repository-scoped version of the 'read_replace_refs' global. The global still has its purpose: it is disabled process-wide by the GIT_NO_REPLACE_OBJECTS environment variable or by a call to disable_replace_refs() in some specific Git commands. Since we already encapsulated the use of the constant inside replace_refs_enabled(), we can perform the initialization inside that method, if necessary. This solves the problem of forgetting to check the config, as we will check it before returning this value. Due to this encapsulation, the global can move to be static within replace-object.c. There is an interesting behavior change possible here: we now have a repository-scoped understanding of this config value. Thus, if there was a command that recurses into submodules and might follow replace refs, then it would now respect the core.useReplaceRefs config value in each repository. 'git grep --recurse-submodules' is such a command that recurses into submodules in-process. We can demonstrate the granularity of this config value via a test in t7814. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-06 13:24:37 +00:00
/*
* This indicator determines whether replace references should be
* respected process-wide, regardless of which repository is being
* using at the time.
*/
static int read_replace_refs = 1;
void disable_replace_refs(void)
{
read_replace_refs = 0;
}
int replace_refs_enabled(struct repository *r)
{
repository: create read_replace_refs setting The 'read_replace_refs' global specifies whether or not we should respect the references of the form 'refs/replace/<oid>' to replace which object we look up when asking for '<oid>'. This global has caused issues when it is not initialized properly, such as in b6551feadfd (merge-tree: load default git config, 2023-05-10). To make this more robust, move its config-based initialization out of git_default_config and into prepare_repo_settings(). This provides a repository-scoped version of the 'read_replace_refs' global. The global still has its purpose: it is disabled process-wide by the GIT_NO_REPLACE_OBJECTS environment variable or by a call to disable_replace_refs() in some specific Git commands. Since we already encapsulated the use of the constant inside replace_refs_enabled(), we can perform the initialization inside that method, if necessary. This solves the problem of forgetting to check the config, as we will check it before returning this value. Due to this encapsulation, the global can move to be static within replace-object.c. There is an interesting behavior change possible here: we now have a repository-scoped understanding of this config value. Thus, if there was a command that recurses into submodules and might follow replace refs, then it would now respect the core.useReplaceRefs config value in each repository. 'git grep --recurse-submodules' is such a command that recurses into submodules in-process. We can demonstrate the granularity of this config value via a test in t7814. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-06 13:24:37 +00:00
if (!read_replace_refs)
return 0;
if (r->gitdir) {
prepare_repo_settings(r);
return r->settings.read_replace_refs;
}
/* repository has no objects or refs. */
return 0;
}