version 0.003; 2014-05-05
* bugfix: on Perl 5.6, repair a dodgy workaround that could cause
magical (e.g., tainted) arguments to lose their magic flags
* bugfix: build custom ops in a way that satisfies an unnecessary
assertion in debugging Perl builds
* new function shash_idle() to prevent an idle handle keeping an
obsolete data file around
* when tidying, include a non-zero constant term in the computation
of the new file size, to avoid cycling data files very rapidly when
the shared hash contains little data
* count events for profiling and debugging, counters accessed
through new functions shash_tally_get(), shash_tally_zero(), and
shash_tally_gzero()
* make the constant shash_referential_handle also available as a class
method on Hash::SharedMem::Handle
* when attempting to unlink a file, other than for cleanup of an
operation that died, if unlinking fails for reasons other than ENOENT
or EBUSY, report the error, rather than silently ignoring it
* cooperate in the tainting system, mainly imitating the taint behaviour
of regular file handles
* support using the module in multiple threads simultaneously,
including, on Perl 5.8.9 and later, duplicating handles for thread
spawning
* cope on Cygwin, which offers a fraudulent openat(2) et al
* avoid a C99 declaration-after-statement construction
* avoid using "NULL" for null function pointers, for C compiler
portability
* be cleverer about the asymmetry of key ranges in the B-tree structure,
saving about one key comparison per data operation
* use cursors internally, so that the key has to be resolved only
once for each combined read-and-write operation (shash_gset()
and shash_cset())
* when attempting a data file rollover, if the attempt fails due to
a conflicting update from another process, unmap the abortive data
file before attempting to unlink it, so that the unlink will succeed
on OSes that need a mapped file to remain linked
* in documentation, comment on the inefficiency that occurs when the
shared hash doesn't fit into RAM
* in documentation, comment on the Unicode bug in the treatment of
filenames
* don't uselessly attempt to hook into B::Deparse on Perls where custom
ops aren't registered and so the hook can't work
* don't uselessly attempt to hook into B::Deparse for the
shash_referential_handle constant which isn't a custom op type
* test concurrency with real concurrent racing processes
* test that a forked handle works correctly
* include magic(5) file, describing the identifying part of the format
of shared hash files, in the distribution
* manage destruction of shared hash handles through magic rather than
a DESTROY method, for a small speedup
* restructure the internal representation of directory references,
for a small simplification of uses of the references
* in test suite, extend to shash_tidy() some patterns of tests that
cover most operators and which were missed when shash_tidy() was
added to the module
* slight refactoring of C code
* on systems that lack mmap(2), detect the problem cleanly and report
it in a way that CPAN Testers understand
* in design document and code, use the more standard term "fanout"
instead of "splay"
* take todo notes out of code comments
version 0.002; 2014-03-25
* new function shash_tidy() to make data file rollover happen at a
convenient time
* in many error messages, state more specifically and consistently
what kind of action has failed
* in documentation, consistently describe the content of a shared hash
as "content" rather than "contents"
version 0.001; 2014-03-23
* bugfix: avoid overflowing a directory entry buffer on OSes where
struct dirent is not a suitable size for a buffer
* bugfix: avoid overflowing a filename buffer when time exceeds the
32-bit range (a year 2038 problem) or PIDs are larger than 32 bits
* ensure reliable behaviour across fork(2), by not holding on to
allocated data file space between write operations
* create all data files with the same permission bits as the master
file, so that the permissions set when the shash was created stick,
and the umask at the time of shash operations doesn't matter
* attempt to give all data files the same group and owner as the master
file, so that permissions behave as consistently as possible
* new exported constant shash_referential_handle to indicate whether
shared hash handles constitute first-class references to the
underlying files
* detect non-octet string values for key and value parameters reliably
and early, consistently signalling the error
* detect non-string values for filename parameters, signalling the error
* process get magic on each parameter exactly once per hash operation
(though users of the tied interface are at the mercy of the tying
infrastructure, which doesn't have such clean behaviour)
* when attempting to clean a shash directory, if listing the directory
fails, report the error, rather than silently abandoning the cleaning
attempt
* when attempting to generate a new data file, if the size is so large
as to cast to a negative off_t value, detect it early and report
EFBIG, rather than going ahead to create the file and detect the
error at ftruncate(2) time
* if ftruncate(2) reports that a requested file size is too big using
errno EINVAL, report it as the more enlightening EFBIG
* when attempting to iterate a shash directory, if opening the directory
fails, detect it and report the real error, rather than going ahead
to fdopendir(3) and detecting its EBADF
* when reporting an error including the name of a shash, to match
user expectations use the characters of the filename scalar that
was supplied upon opening, even though the octets of the scalar's
internal representation are what are actually used as the filename
* automatically detect and adapt to the machine architecture's line
and page size, to improve performance on architectures other than
IA32/AMD64
* port to pre-5.14 Perls, back to 5.6
* automatically use the -lrt library on systems where it is required
in order to get access to clock_gettime(2)
* cope on systems where openat(2) et al are not available, either not
defined by the headers, or defined but not functioning
* cope on systems where clock_gettime(2) is not available, either not
defined by the headers, or defined but not functioning
* cope on systems where O_CLOEXEC is not available, either not defined
by the headers, or defined but not honoured (or not accepted) by
the kernel
* when iterating a shash directory, open a new file descriptor rather
than duplicate the existing one, avoiding portability problems with
F_DUPFD_CLOEXEC
* use symbolic constants for file permission bits, for portability to
systems where they have non-traditional values
* cope on systems where the headers don't define MAP_FAILED
* check at compile time that the word data type is of exactly the
required size
* on Perls that support it, hook into B::Deparse to make the custom
ops deparse nicely
* many new tests
* document the effects of file-level operations on shared hash
directories
* document the tied(%shash) operator as part of the tied interface
* clarify documentation about permitted keys and values
* in documentation, mention serialisation and refer to Sereal
* perform string equality comparisons more efficiently by specific
code separate from ordering comparisons
* use more efficient variants of Perl API functions where available
* use the Perl-version-dependent matching data type to save
PL_tmps_floor, rather than an invariant sufficiently-large type
* declare C functions as inline where it'll help for compilers that
need the hint
* make some printf operations cheaper by taking advantage of Perl's
requirement that the C int type is at least 32 bits
* shuffle C struct members for better packing on 32-bit systems
* small clarifications to design document
* slight refactoring of C code
* avoid some C compiler warnings
version 0.000; 2014-02-27
* initial released version