git/attr.h, branch v2.13.2

pathspec: allow querying for attributes

2017-03-13T22:28:54Z

The pathspec mechanism is extended via the new ":(attr:eol=input)pattern/to/match" syntax to filter paths so that it requires paths to not just match the given pattern but also have the specified attrs attached for them to be chosen. Based on a patch by Stefan Beller Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano

attr: reformat git_attr_set_direction() function

2017-02-01T21:46:53Z

Move the 'git_attr_set_direction()' up to be closer to the variables that it modifies as well as a small formatting by renaming the variable 'new' to 'new_direction' so that it is more descriptive. Update the comment about how 'direction' is used to read the state of the world. It should be noted that callers of 'git_attr_set_direction()' should ensure that other threads are not making calls into the attribute system until after the call to 'git_attr_set_direction()' completes. This function essentially acts as reset button for the attribute system and should be handled with care. Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano

attr: store attribute stack in attr_check structure

2017-02-01T21:46:53Z

The last big hurdle towards a thread-safe API for the attribute system is the reliance on a global attribute stack that is modified during each call into the attribute system. This patch removes this global stack and instead a stack is stored locally in each attr_check instance. This opens up the opportunity for future optimizations to customize the attribute stack for the attributes that a particular attr_check struct is interested in. One caveat with pushing the attribute stack into the attr_check structure is that the attribute system now needs to keep track of all active attr_check instances. Due to the direction mechanism the stack needs to be dropped when the direction is switched. In order to ensure correctness when the direction is changed the attribute system needs to iterate through all active attr_check instances and drop each of their stacks. Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano

attr: tighten const correctness with git_attr and match_attr

2017-02-01T21:46:53Z

Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano

attr: eliminate global check_all_attr array

2017-02-01T21:46:53Z

Currently there is a reliance on 'check_all_attr' which is a global array of 'attr_check_item' items which is used to store the value of each attribute during the collection process. This patch eliminates this global and instead creates an array per 'attr_check' instance which is then used in the attribute collection process. This brings the attribute system one step closer to being thread-safe. Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano

attr: use hashmap for attribute dictionary

2017-02-01T21:46:53Z

The current implementation of the attribute dictionary uses a custom hashtable. This modernizes the dictionary by converting it to the builtin 'hashmap' structure. Also, in order to enable a threaded API in the future add an accompanying mutex which must be acquired prior to accessing the dictionary of interned attributes. Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano

attr: retire git_check_attrs() API

2017-02-01T21:46:52Z

Since nobody uses the old API, make it file-scope static, and update the documentation to describe the new API. Signed-off-by: Junio C Hamano Signed-off-by: Stefan Beller Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano

attr: convert git_all_attrs() to use "struct attr_check"

2017-02-01T21:46:52Z

This updates the other two ways the attribute check is done via an array of "struct attr_check_item" elements. These two niches appear only in "git check-attr". * The caller does not know offhand what attributes it wants to ask about and cannot use attr_check_initl() to prepare the attr_check structure. * The caller may not know what attributes it wants to ask at all, and instead wants to learn everything that the given path has. Such a caller can call attr_check_alloc() to allocate an empty attr_check, and then call attr_check_append() to add attribute names one by one. Signed-off-by: Junio C Hamano Signed-off-by: Stefan Beller Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano

attr: (re)introduce git_check_attr() and struct attr_check

2017-02-01T21:46:52Z

A common pattern to check N attributes for many paths is to (1) prepare an array A of N attr_check_item items; (2) call git_attr() to intern the N attribute names and fill A; (3) repeatedly call git_check_attrs() for path with N and A; A look-up for these N attributes for a single path P scans the entire attr_stack, starting from the .git/info/attributes file and then .gitattributes file in the directory the path P is in, going upwards to find .gitattributes file found in parent directories. An earlier commit 06a604e6 (attr: avoid heavy work when we know the specified attr is not defined, 2014-12-28) tried to optimize out this scanning for one trivial special case: when the attribute being sought is known not to exist, we do not have to scan for it. While this may be a cheap and effective heuristic, it would not work well when N is (much) more than 1. What we would want is a more customized way to skip irrelevant entries in the attribute stack, and the definition of irrelevance is tied to the set of attributes passed to git_check_attrs() call, i.e. the set of attributes being sought. The data necessary for this optimization needs to live alongside the set of attributes, but a simple array of git_attr_check_elem simply does not have any place for that. Introduce "struct attr_check" that contains N, the number of attributes being sought, and A, the array that holds N attr_check_item items, and a function git_check_attr() that takes a path P and this structure as its parameters. This structure can later be extended to hold extra data necessary for optimization. Also, to make it easier to write the first two steps in common cases, introduce git_attr_check_initl() helper function, which takes a NULL-terminated list of attribute names and initialize this structure. Signed-off-by: Junio C Hamano Signed-off-by: Stefan Beller Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano

attr: rename function and struct related to checking attributes

2017-02-01T21:46:52Z

The traditional API to check attributes is to prepare an N-element array of "struct git_attr_check" and pass N and the array to the function "git_check_attr()" as arguments. In preparation to revamp the API to pass a single structure, in which these N elements are held, rename the type used for these individual array elements to "struct attr_check_item" and rename the function to "git_check_attrs()". Signed-off-by: Junio C Hamano Signed-off-by: Stefan Beller Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano