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- Added a description of the thread-safe stdin/stdout/stderr behaviour.

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git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@14900 87f5fb63-7c3d-0410-a384-fd976d0f7a62
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Olaf Barthel
2005-03-25 08:50:10 +00:00
parent 8edfcc3f86
commit 1fbe4bd0a5
1 changed files with 13 additions and 2 deletions
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documentation/README.html
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@ -57,11 +57,13 @@ when it starts up. This is controlled via the <tt>__stack_size</tt> variable (se
<p>I added some <tt>amiga.lib</tt> and <tt>debug.lib</tt> functionality to the library, but don't
count on it to be complete.</p>
<h3>2.1 Thread-safety</h3>
<p>The library code is supposed to be thread-safe if built with the <tt>__THREAD_SAFE</tt>
preprocesssor symbold defined. Note that 'thread-safe' does <em>not</em> mean
'reentrant'. Multiple callers for certain library functions are permitted, but
not for all of them. For example, <tt>mkdtemp()</tt> is not thread-safe, and neither is
<tt>rand()</tt> or <tt>localtime()</tt>. But as per POSIX 1003.1c-1995 there are thread-safe
<tt>rand()</tt> or <tt>localtime()</tt>. But as per <b>POSIX 1003.1c-1995</b> there are thread-safe
variants of <tt>rand()</tt> and <tt>localtime()</tt> called <tt>rand_r()</tt>, <tt>localtime_r()</tt>, and others.
The use of the socket I/O functions is still problematic because the
underlying <tt>bsdsocket.library</tt> API is not supposed to be used by any process
@ -71,10 +73,19 @@ error code left by the last caller.</p>
<p>Take care: thread-safety does not imply that you can have multiple callers
access and close the same file. There is no resource tracking to that degree
yet. All the thread-safety tries to afford you is not to get into big trouble
yet. All that the thread-safety tries to afford you is not to get into big trouble
if simultaneous and overlapping accesses to files, memory allocation and other
resources are taking place.</p>
<p> Also take care with file I/O involving the <tt>stdin</tt>/<tt>stdout</tt>/<tt>stderr</tt>
streams; read/write operations on these streams will be mapped to the <tt>Input()</tt>/</tt>Output()</tt>/<tt>ErrorOutput()</tt>
file handles of the process performing these operations. Since only this small set of
operations is mapped, functions such as <tt>fcntl()</tt> or <tt>select()</tt> will not
work on the <tt>stdin</tt>/<tt>stdout</tt>/<tt>stderr</tt> streams and the corresponding
file descriptors <tt>STDIN_FILENO</tt>/<tt>STDOUT_FILENO</tt>/<tt>STDERR_FILENO</tt>.
It is therefore strongly recommended to use the thread-safe library only for applications
which can cope with the limitations described above.</p>
<h2>3. What does it not do?</h2>