library/io.call_system.m:
Move the code in the "system access predicates" section of io.m
to this new module.
library/io.environment.m:
Move the predicates dealing with environment variables in io.m
to this new module.
library/io.m:
Delete the code moved to the new modules.
Leave behind in io.m "forwarding predicates", predicates that do nothing
except call the moved predicates in the new modules, to provide backward
compatibility. But do mark the forwarding predicates as obsolete,
to tell people to update their (at their leisure, since the obsoleteness
warning can be turned off).
Also leave behind in io.m the definitions of the types used
by some parameters of some of the moved predicates.
library/MODULES_DOC:
List the new modules among the documented modules.
library/library.m:
List the new modules, including io.file.m (added in a previous change)
among the documented standard library modules.
NEWS:
Announce the changes.
browser/browse.m:
browser/interactive_query.m:
compiler/fact_table.m:
compiler/handle_options.m:
compiler/make.module_target.m:
compiler/mercury_compile_main.m:
compiler/module_cmds.m:
compiler/optimize.m:
compiler/options_file.m:
deep_profiler/conf.m:
deep_profiler/mdprof_cgi.m:
deep_profiler/mdprof_test.m:
library/io.file.m:
mdbcomp/trace_counts.m:
ssdb/ssdb.m:
tests/general/environment.m:
tests/hard_coded/closeable_channel_test.m:
tests/hard_coded/setenv.m:
tests/hard_coded/system_sort.m:
Call the moved predicates directly in their new modules,
not indirectly through io.m.
library/thread.closeable_channel.m:
Rename the `empty' result of closeable_channel.try_take to
`would_block'.
tests/hard_coded/closeable_channel_test.exp:
tests/hard_coded/closeable_channel_test.m:
Update test case.
This is a plausible sequence of events leading to a failure in the
hard_coded/closeable_channel_test.m test case:
thread A thread B
-------- --------
close(Chan)
channel.take(Chan)
-> mvar.read(Head)
-> semaphore.wait(Full)
is_closed(Chan, IsClosed)
-> mvar.try_read(Hole)
-> semaphore.try_wait(Full)
Thread B tries to take the next item from the channel, during which time
it holds the Full semaphore of the mvar at the read end of the channel.
Thread A attempts to verify that the channel is really closed.
It tries to read from the mvar at the write end of the channel, which is
the same mvar as thread B is reading from (because the channel is empty).
Thread A cannot acquire the Full semaphore of the mvar as the semaphore
is being held by thread B, resulting in the call is_closed(Chan, IsClosed)
to return with IsClosed = no.
library/thread.closeable_channel.m:
Delete the is_closed predicate. It was of questionable utility
anyway.
tests/hard_coded/closeable_channel_test.m:
Delete call to is_closed in test case.
