This patch delays writing in-memory changes out, if transaction is
running.
'_getfsnow()' is defined as a function, to hook it easily for
ambiguous timestamp tests (see also fakedirstatewritetime.py)
'if tr:' code path in this patch is still disabled at this revision,
because there is no client invoking 'dirstate.write()' with repo
object.
BTW, this patch changes 'dirstate.invalidate()' semantics around
'dirstate.write()' in a transaction scope:
before:
with repo.transaction():
dirstate.CHANGE('A')
dirstate.write() # change for A is written out here
dirstate.CHANGE('B')
dirstate.invalidate() # discards only change for B
after:
with repo.transaction():
dirstate.CHANGE('A')
dirstate.write() # change for A is still kept in memory
dirstate.CHANGE('B')
dirstate.invalidate() # discards changes for A and B
Fortunately, there is no code path expecting the former, at least, in
Mercurial itself, because 'dirstateguard' was introduced to remove
such 'dirstate.invalidate()'.
On recent OS, 'stat.st_mtime' has a double precision floating point
value to represent nano seconds, but it is not wide enough for actual
file timestamp: nowadays, only 52 - 32 = 20 bit width is available for
decimal places in sec.
Therefore, casting it to 'int' may cause unexpected result. See also
changeset 8102a3981272 fixing issue4836 for detail.
For example, changed file A may be treated as "clean" unexpectedly in
steps below. "rounded now" is the value gotten by rounding via
'int(st.st_mtime)' or so.
---------------------+--------------------+------------------------
"now" | | timestamp of A (time_t)
float rounded time_t| action | FS dirstate
------ ------- ------+--------------------+-------- ---------------
N+.nnn N N | | --- ---
| update file A | N
| dirstate.normal(A) | N
N+.999 N+1 N | |
| dirstate.write() | N (*1)
| : |
| change file A | N
| : |
N+1.00 N+1 N+1 | |
| "hg status" (*2) | N N
------ ------- ------+--------------------+-------- ---------------
Timestamp N of A in dirstate isn't dropped at (*1), because "rounded
now" is N+1 at that time, even if 'st_mtime' in 'time_t' is still N.
Then, file A is unexpectedly treated as "clean" at (*2) in this case.
For consistent handling of 'stat.st_mtime', this patch makes
'pack_dirstate()' take 'now' argument not in floating point but in
integer.
This patch makes 'PyArg_ParseTuple()' in 'pack_dirstate()' use format
'i' (= checking type mismatch or overflow), even though it is ensured
that 'now' is in the range of 32bit signed integer by masking with
'_rangemask' (= 0x7fffffff) on caller side.
It should be cheaper enough than packing itself, and useful to
detect that legacy code invokes 'pack_dirstate()' with 'now' in
floating point value.
This extension fakes 'now' for 'parsers.pack_dirstate()' to emulate
invoking 'dirstate.write()' at the specific time, only when
'dirstate.write()' is invoked via functions below:
- 'workingctx._checklookup()' (= 'repo.status()')
- 'committablectx.markcommitted()'
This is useful to reproduce timing critical issues fixed in subsequent
patches.
