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a7c60cfc
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2009-01-03T02:41:26
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Add basic support to read pack-*.idx v1 and v2 files
The index data is mapped into memory and then scanned using a
binary search algorithm to locate the matching entry for the
supplied git_oid. The standard fanout hash trick is applied to
reduce the search space by 8 iterations.
Since the v1 and v2 file formats differ in their search function,
due to the different layouts used for the object records, we use
two different search implementations and a virtual function pointer
to jump to the correct version of code for the current pack index.
The single function jump per-pack should be faster then computing
a branch point inside the inner loop of a common binary search.
To improve concurrency during read operations the pack lock is only
held while verifying the index is actually open, or while opening
the index for the first time. This permits multiple concurrent
readers to scan through the same index.
If an invalid index file is opened we close it and mark the
git_pack's invalid bit to true. The git_pack structure is kept
around in its parent git_packlist, but the invalid bit will cause
all future readers to skip over the pack entirely. Pruning the
invalid entries is relatively unimportant because they shouldn't
be very common, a $GIT_DIRECTORY/objects/pack directory tends to
only have valid pack files.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
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2c4b7707
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2008-12-31T16:06:48
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Add git__fmt as an easier to use snprintf
Checking the return value of snprintf is a pain, as it must be
>= 0 and < sizeof(buffer). git__fmt is a simple wrapper to
perform these checks.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
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9eb79764
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2008-12-31T14:35:39
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Add string utility functions for prefix and suffix compares
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
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5673434f
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2008-12-31T07:34:43
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Undefine malloc,strdup,calloc before redefining them
Some systems may use cpp macros to define these functions, glibc
appears to be one of them.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
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64a47c01
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2008-12-30T23:21:36
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Wrap malloc and friends and report out of memory as GIT_ENOMEM
We now forbid direct use of malloc, strdup or calloc within the
library and instead use wrapper functions git__malloc, etc. to
invoke the underlying library malloc and set git_errno to a no
memory error code if the allocation fails.
In the future once we have pack objects in memory we are likely
to enhance these routines with garbage collection logic to purge
cached pack data when allocations fail. Because the size of the
function will grow somewhat large, we don't want to mark them for
inline as gcc tends to aggressively inline, creating larger than
expected executables.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
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3a2aabdc
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2008-11-22T14:44:47
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Add util.h - utility macros
ARRAY_SIZE() et al go in util.h, included from common.h
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
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