Re: [PATCH v5 1/2] add `config_set` API for caching config-like files
From: Ramsay Jones <hidden>
Date: 2016-06-15 23:01:49
On 06/07/14 08:19, Tanay Abhra wrote:
quoted hunk ↗ jump to hunk
Currently `git_config()` uses a callback mechanism and file rereads for config values. Due to this approach, it is not uncommon for the config files to be parsed several times during the run of a git program, with different callbacks picking out different variables useful to themselves. Add a `config_set`, that can be used to construct an in-memory cache for config-like files that the caller specifies (i.e., files like `.gitmodules`, `~/.gitconfig` etc.). Add two external functions `git_configset_get_value` and `git_configset_get_value_multi` for querying from the config sets. `git_configset_get_value` follows `last one wins` semantic (i.e. if there are multiple matches for the queried key in the files of the configset the value returned will be the last entry in `value_list`). `git_configset_get_value_multi` returns a list of values sorted in order of increasing priority (i.e. last match will be at the end of the list). Add type specific query functions like `git_configset_get_bool` and similar. Add a default `config_set`, `the_config_set` to cache all key-value pairs read from usual config files (repo specific .git/config, user wide ~/.gitconfig and the global /etc/gitconfig). `the_config_set` uses a single hashmap populated using `git_config()`. Add two external functions `git_config_get_value` and `git_config_get_value_multi` for querying in a non-callback manner from `the_config_set`. Also, add type specific query functions that are implemented as a thin wrapper around the `config_set` API. Signed-off-by: Tanay Abhra <redacted> --- Documentation/technical/api-config.txt | 134 +++++++++++++++ Makefile | 1 + cache.h | 34 ++++ config-hash.c | 297 +++++++++++++++++++++++++++++++++ config.c | 3 + 5 files changed, 469 insertions(+) create mode 100644 config-hash.cdiff --git a/Documentation/technical/api-config.txt b/Documentation/technical/api-config.txt index 230b3a0..bdf86d0 100644 --- a/Documentation/technical/api-config.txt +++ b/Documentation/technical/api-config.txt@@ -77,6 +77,81 @@ To read a specific file in git-config format, use `git_config_from_file`. This takes the same callback and data parameters as `git_config`. +Querying For Specific Variables +------------------------------- + +For programs wanting to query for specific variables in a non-callback +manner, the config API provides two functions `git_config_get_value` +and `git_config_get_value_multi`. They both read values from an internal +cache generated previously from reading the config files. + +`int git_config_get_value(const char *key, const char **value)`:: + + Finds the highest-priority value for the configuration variable `key`, + stores the pointer to it in `value` and returns 0. When the + configuration variable `key` is not found, returns 1 without touching + `value`. The caller should not free or modify `value`, as it is owned + by the cache. + +`const struct string_list *git_config_get_value_multi(const char *key)`:: + + Finds and returns the value list, sorted in order of increasing priority + for the configuration variable `key`. When the configuration variable + `key` is not found, returns NULL. The caller should not free or modify + the returned pointer, as it is owned by the cache. + +`void git_config_clear(void)`:: + + Resets and invalidate the config cache. + +The config API also provides type specific API functions which do conversion +as well as retrieval for the queried variable, including: + +`int git_config_get_int(const char *key, int *dest)`:: + + Finds and parses the value to an integer for the configuration variable + `key`. Dies on error; otherwise, stores pointer to the parsed integer in
... stores the value of the parsed integer in `dest` ...
+ `dest` and returns 0. When the configuration variable `key` is not found, + returns 1 without touching `dest`. + +`int git_config_get_ulong(const char *key, unsigned long *dest)`:: + + Similar to `git_config_get_int` but for unsigned longs. + +`int git_config_get_int(const char *key, int *dest)`::
-----------------------^^^ git_config_get_bool
+ + Finds and parses the value into a boolean value, for the configuration + variable `key`respecting keywords like "true" and "false". Integer + values are converted into true/false values (when they are non-zero or + zero, respectively). Other values cause a die(). If parsing is successful, + stores the pointer to the parsed result in `dest` and returns 0. When the
... stores the value of the parsed result in `dest` ...
+ configuration variable `key` is not found, returns 1 without touching + `dest`. + +`int git_config_get_bool_or_int(const char *key, int *is_bool, int *dest)`:: + + Similar to `git_config_get_bool`, except that integers are copied as-is, + and `is_bool` flag is unset. + +`int git_config_get_maybe_bool(const char *key, int *dest)`:: + + Similar to `git_config_get_bool`, except that it returns -1 on error + rather than dying. + +`int git_config_get_string(const char *key, const char **dest)`:: + + Allocates and copies the retrieved string into the `dest` parameter for + the configuration variable `key`; if NULL string is given, prints an + error message and returns -1. When the configuration variable `key` is + not found, returns 1 without touching `dest`. + +`int git_config_get_pathname(const char *key, const char **dest)`:: + + Similar to `git_config_get_string`, but expands `~` or `~user` into + the user's home directory when found at the beginning of the path. + +See test-config.c for usage examples. +
Sorry, I didn't have time to do more than squint at the code, but at first glance it looks good. ATB, Ramsay Jones