[project @ 2001-05-18 16:54:04 by simonmar]

I/O library rewrite
-------------------

This commit replaces the old C/Haskell I/O implementation with a new
Haskell-only one using the new FFI & hsc2hs.

main points:

   - lots of code deleted: we're about 3000 lines of C lighter,
     but the amount of Haskell code is about the same.

   - performance is ok: some operations are faster, others are
     slower.  There's still some tuning to do, though.

   - the new library is designed to handle read/write streams
     much better: a read/write stream gets a special kind of
     handle internally called a "DuplexHandle", which actually
     contains two separate handles, one for writing and one for
     reading.  The upshot is that you can do simultaneous reading
     and writing to/from a socket or FIFO without any locking
     problems.  The effect is similar to calling socketToHandle
     twice, except that finalization works properly (creating
     two separate Handles could lead to the socket being closed
     too early when one of the Handles is GC'd).

   - hConnectTo and withHandleFor are gone (no one responded to
     my mail on GHC users, but we can always bring 'em back if
     necessary).

   - I made a half-hearted attempt at keeping the system-specific
     code in one place: see PrelPosix.hsc.

   - I've rearranged the I/O tests and added lots more.
     ghc/tests/lib/IO now contains Haskell 98-only IO tests,
     ghc/test/lib/{IOExts, Directory, Time} now contain tests for
     the relevant libraries.  I haven't quite finished in here yet,
     the IO tests work but the others don't yet.

   - I haven't done anything about Unicode yet, but now we can
     start to discuss what needs doing here.  The new library
     is using MutableByteArrays for its buffers because that
     turned out to be a *lot* easier (and quicker) than malloc'd
     buffers - I hope this won't cause trouble for unicode
     translations though.

WARNING: Windows users refrain from updating until we've had a chance
to fix any issues that arise.

Testing: the basic H98 stuff has been pretty thoroughly tested, but
the new duplex handle stuff is still a little green.

1 files changed, 16 insertions, 60 deletions

diff --git a/ghc/lib/std/cbits/inputReady.c b/ghc/lib/std/cbits/inputReady.c
index a7f1068ef0..00b2d923aa 100644
--- a/ghc/lib/std/cbits/inputReady.c
+++ b/ghc/lib/std/cbits/inputReady.c
@@ -1,7 +1,7 @@
 /* 
  * (c) The GRASP/AQUA Project, Glasgow University, 1994-1998
  *
- * $Id: inputReady.c,v 1.6 1999/12/08 15:47:08 simonmar Exp $
+ * $Id: inputReady.c,v 1.7 2001/05/18 16:54:06 simonmar Exp $
  *
  * hReady Runtime Support
  */
@@ -11,87 +11,43 @@
 #define NON_POSIX_SOURCE  
 #endif
 
-#include "Rts.h"
-#include "stgio.h"
-
-#ifdef HAVE_SYS_TYPES_H
-#include <sys/types.h>
-#endif
-
-#ifdef _AIX 
-/* this is included from sys/types.h only if _BSD is defined. */
-/* Since it is not, I include it here. - andre */
-#include <sys/select.h>
-#endif
-
-#ifdef HAVE_UNISTD_H
-#include <unistd.h>
-#endif
-
-#ifdef HAVE_FCNTL_H
-#include <fcntl.h>
-#endif
-
-#ifdef HAVE_SYS_TIME_H
-#include <sys/time.h>
-#endif
+#include "HsStd.h"
 
 /*
- * inputReady(ptr, msecs) checks to see whether input is available
- * on the file object 'ptr', timing out after (approx.) 'msec' milliseconds.
- * Input meaning 'can I safely read at least a *character* from this file
- * object without blocking?'
- * 
- * If the file object has a non-empty buffer, the test is trivial. If not,
- * we select() on the (readable) file descriptor.
- *
- * Notice that for file descriptors connected to ttys in non-canonical mode
- * (i.e., it's buffered), inputReady will not return true until a *complete
- * line* can be read.
+ * inputReady(fd) checks to see whether input is available on the file
+ * descriptor 'fd'.  Input meaning 'can I safely read at least a
+ * *character* from this file object without blocking?'
  */
-
-StgInt
-inputReady(ptr, msecs)
-StgForeignPtr ptr;
-StgInt msecs;
+int
+inputReady(int fd, int msecs)
 {
-    IOFileObject* fo = (IOFileObject*)ptr;
-    int fd, maxfd, ready;
+    int maxfd, ready;
 #ifndef mingw32_TARGET_OS
     fd_set rfd;
     struct timeval tv;
 #endif
 
-    if ( FILEOBJ_IS_EOF(fo) )
-	return 0;
-
-    if ( !FILEOBJ_BUFFER_EMPTY(fo) ) {
-	   /* Don't look any further, there's stuff in the buffer */
-	   return 1;
-    }
-
 #ifdef mingw32_TARGET_OS
     return 1;
 #else
-    fd = fo->fd;
-
-    /* Now try to get a character */
     FD_ZERO(&rfd);
     FD_SET(fd, &rfd);
-    /* select() will consider the descriptor set in the range of 0 to (maxfd-1) */
+
+    /* select() will consider the descriptor set in the range of 0 to
+     * (maxfd-1) 
+     */
     maxfd = fd + 1;
     tv.tv_sec  = msecs / 1000;
     tv.tv_usec = msecs % 1000;
+
     while ((ready = select(maxfd, &rfd, NULL, NULL, &tv)) < 0 ) {
       if (errno != EINTR ) {
-		cvtErrno();
-		stdErrno();
-                ready = -1;
-      		break;
+          return -1;
       }
    }
 
-    /* 1 => Input ready, 0 => time expired  (-1 error) */
+    /* 1 => Input ready, 0 => not ready, -1 => error */
     return (ready);
+
 #endif
 }