clear_##slabname() frees only the memory allocated for a commit slab
itself, but entries in the commit slab might own additional memory
outside the slab that should be freed as well. We already have (at
least) one such commit slab, and this patch series is about to add one
more.
To free all additional memory owned by entries on the commit slab the
user of such a slab could iterate over all commits it knows about,
peek whether there is a valid entry associated with each commit, and
free the additional memory, if any. Or it could rely on intimate
knowledge about the internals of the commit slab implementation, and
could itself iterate directly through all entries in the slab, and
free the additional memory. Or it could just leak the additional
memory...
Introduce deep_clear_##slabname() to allow releasing memory owned by
commit slab entries by invoking the 'void free_fn(elemtype *ptr)'
function specified as parameter for each entry in the slab.
Use it in get_shallow_commits() in 'shallow.c' to replace an
open-coded iteration over a commit slab's entries.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Ever since 862e730ec1 (commit-slab: introduce slabname##_peek()
function, 2015-05-14) the slabname##_peek() function is documented as:
This function is similar to indegree_at(), but it will return NULL
until a call to indegree_at() was made for the commit.
This, however, is usually not the case. If indegree_at() allocates
memory, then it will do so not only for the single commit it got as
parameter, but it will allocate a whole new, ~512kB slab. Later on,
if any other commit's 'index' field happens to point into an already
allocated slab, then indegree_peek() for such a commit will return a
valid non-NULL pointer, pointing to a zero-initialized location in the
slab, even if no indegree_at() call has been made for that commit yet.
Update slabname##_peek()'s documentation to clarify this.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
define_shared_commit_slab() could be used in a header file to define a
commit-slab. One of these C files must include commit-slab-impl.h and
"call" implement_shared_commit_slab().
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The struct declaration and implementation macros are moved to
commit-slab-hdr.h and commit-slab-impl.h respectively.
This right now is not needed for current users but if we make a public
commit-slab type, we may want to avoid including the slab
implementation in a header file which gets replicated in every c file
that includes it.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Replace occurrences of `free(ptr); ptr = NULL` which weren't caught by
the coccinelle rule. These fall into two categories:
- free/NULL assignments one after the other which coccinelle all put
on one line, which is functionally equivalent code, but very ugly.
- manually spotted occurrences where the NULL assignment isn't right
after the free() call.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The gigantic define_commit_slab() macro repeats the definition of a
static variable that occurs earlier in the macro text. The purpose of
the repeated definition at the end of the macro is that it takes the
semicolon that occurs where the macro is used.
We cannot just remove the first definition of the variable because it
is referenced elsewhere in the macro text, and defining the macro later
would produce undefined identifier errors. We cannot have a "forward"
declaration, either. (This works only with "extern" global variables.)
The solution is to use a declaration of a struct that is already defined
earlier. This language construct can serve the same purpose as the
duplicated static variable definition, but without the confusion.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Memory use reduction when commit-slab facility is used to annotate
sparsely (which is not recommended in the first place).
* jc/commit-slab:
commit-slab: introduce slabname##_peek() function
There is no API to ask "Does this commit have associated data in
slab?". If an application wants to (1) parse just a few commits at
the beginning of a process, (2) store data for only these commits,
and then (3) start processing many commits, taking into account the
data stored (for a few of them) in the slab, the application would
use slabname##_at() to allocate a space to store data in (2), but
there is no API other than slabname##_at() to use in step (3). This
allocates and wastes new space for these commits the caller is only
interested in checking if they have data stored in step (2).
Introduce slabname##_peek(), which is similar to slabname##_at() but
returns NULL when there is no data already associated to it in such
a use case.
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Callers currently must use init_foo_slab() at runtime before
accessing a slab. For global slabs, it's much nicer if we
can initialize them in BSS, so that each user does not have
to add code to check-and-initialize.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When allocating the slab, the code accidentally computed the array
size from s->slab (an elemtype**). The slab is an array of elemtype*,
however, so we should take the size of *s->slab.
Noticed-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Thomas Rast <tr@thomasrast.ch>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This shuts up compiler warnings about unused functions. No such
warnings are currently triggered, but if someone were to actually
use init_NAME_with_stride() as documented, they would get a warning
about init_NAME() being unused.
While there, write a comment about why the last real declaration of
the variable is without a terminating semicolon, while another
forward declarations have one.
Signed-off-by: Thomas Rast <tr@thomasrast.ch>
Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The clear_$slabname() function was only documented by source code so
far. Write something about it.
Signed-off-by: Thomas Rast <tr@thomasrast.ch>
Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The slab initialization code includes the calculation of the
slab 'elem_size', which is in turn used to determine the size
(capacity) of the slab. Each element of the slab represents an
array, of length 'stride', of 'elemtype'. (Note that it may be
clearer if the define_commit_slab macro parameter was called
'basetype' rather than 'elemtype'). However, the 'elem_size'
calculation incorrectly uses 'sizeof(struct slabname)' in the
expression, rather than 'sizeof(elemtype)'.
Within the slab access routine, <slabname>_at(), the given commit
'index' is transformed into an (slab#, slot#) pair used to address
the required element (a pointer to the first element of the array
of 'elemtype' associated with that commit). The current code to
calculate these address coordinates multiplies the commit index
by the 'stride' which, at least for the slab#, produces the wrong
result. Using the commit index directly, without scaling by the
'stride', produces the correct 'logical' address.
Also, when allocating a new slab, the size of the allocation only
allows for a slab containing elements of single element arrays of
'elemtype'. This should allow for elements of an array of length
'stride' of 'elemtype'. In order to fix this, we need to change
the element size parameter to xcalloc() by multiplying the current
element size (sizeof(**s->slab)) by the s->stride.
Having changed the calculation of the slot#, we now need to convert
the logical 'nth_slot', by scaling with s->stride, into the correct
physical address.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Introduce a header file to define a macro that can define the struct
type, initializer, accessor and cleanup functions to manage a commit
slab. Update the "indegree" topological sort facility using it.
To associate 32 flag bits with each commit, you can write:
define_commit_slab(flag32, uint32);
to declare "struct flag32" type, define an instance of it with
struct flag32 flags;
and initialize it by calling
init_flag32(&flags);
After that, a call to flag32_at() function
uint32 *fp = flag32_at(&flags, commit);
will return a pointer pointing at a uint32 for that commit. Once
you are done with these flags, clean them up with
clear_flag32(&flags);
Callers that cannot hard-code how wide the data to be associated
with the commit be at compile time can use the "_with_stride"
variant to initialize the slab.
Suppose you want to give one bit per existing ref, and paint commits
down to find which refs are descendants of each commit. Saying
typedef uint32 bits320[5];
define_commit_slab(flagbits, bits320);
at compile time will still limit your code with hard-coded limit,
because you may find that you have more than 320 refs at runtime.
The code can declare a commit slab "struct flagbits" like this
instead:
define_commit_slab(flagbits, unsigned char);
struct flagbits flags;
and initialize it by:
nrefs = ... count number of refs ...
init_flagbits_with_stride(&flags, (nrefs + 7) / 8);
so that
unsigned char *fp = flagbits_at(&flags, commit);
will return a pointer pointing at an array of 40 "unsigned char"s
associated with the commit, once you figure out nrefs is 320 at
runtime.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
