Use a writer thread under W32 (arggg)

gpgme/ChangeLog

@@ -1,3 +1,12 @@
+2001-02-28  Werner Koch  <wk@gnupg.org>
+
+	* w32-io.c (destroy_reader): Set sop_me flag.
+	(writer,create_writer,destroy_writer,find_writer,kill_writer): New.
+	(_gpgme_io_write): Use a writer thread to avaoid blocking.
+	(_gpgme_io_close): Cleanup a writer thread
+	(_gpgme_io_select): Repalce tthe faked wait on writing by a real
+	waiting which is now possible due to the use of a writer thread.
+
 2001-02-20  Werner Koch  <wk@gnupg.org>
 
 	* w32-io.c (destroy_reader,kill_reader): New. 

gpgme/w32-io.c

@@ -51,6 +51,9 @@
 #define handle_to_pid(a) ((int)(a))
 
 #define READBUF_SIZE 4096
+#define WRITEBUF_SIZE 4096
+#define MAX_READERS 20
+#define MAX_WRITERS 20
 
 static struct {
     int inuse;
@@ -80,7 +83,6 @@ struct reader_context_s {
 };
 
 
-#define MAX_READERS 20
 static struct {
     volatile int used;
     int fd;
@@ -89,6 +91,34 @@ static struct {
 static int reader_table_size= MAX_READERS;
 DEFINE_STATIC_LOCK (reader_table_lock);
 
+
+struct writer_context_s {
+    HANDLE file_hd;
+    HANDLE thread_hd;	
+    DECLARE_LOCK (mutex);
+
+    int stop_me;
+    int error;
+    int error_code;
+
+    HANDLE have_data;  /* manually reset */
+    HANDLE is_empty;
+    HANDLE stopped;
+    size_t nbytes; 
+    char buffer[WRITEBUF_SIZE];
+};
+
+
+static struct {
+    volatile int used;
+    int fd;
+    struct writer_context_s *context;
+} writer_table[MAX_WRITERS];
+static int writer_table_size= MAX_WRITERS;
+DEFINE_STATIC_LOCK (writer_table_lock);
+
+
+
 static HANDLE
 set_synchronize (HANDLE h)
 {
@@ -239,6 +269,7 @@ create_reader (HANDLE fd)
 static void
 destroy_reader (struct reader_context_s *c)
 {
+    c->stop_me = 1;
     if (c->have_space_ev) 
         SetEvent (c->have_space_ev);
 
@@ -368,27 +399,240 @@ _gpgme_io_read ( int fd, void *buffer, size_t count )
 }
 
 
+
+/*
+ * The writer does use a simple buffering strategy so that we are
+ * informed about write errors as soon as possible (i.e. with the the
+ * next call to the write function
+ */
+static DWORD CALLBACK 
+writer (void *arg)
+{
+    struct writer_context_s *c = arg;
+    DWORD nwritten;
+
+    DEBUG2 ("writer thread %p for file %p started", c->thread_hd, c->file_hd );
+    for (;;) {
+        LOCK (c->mutex);
+        if ( !c->nbytes ) { 
+            if (!ResetEvent (c->have_data) )
+                DEBUG1 ("ResetEvent failed: ec=%d", (int)GetLastError ());
+            UNLOCK (c->mutex);
+            DEBUG1 ("writer thread %p: idle ...", c->thread_hd );
+            WaitForSingleObject (c->have_data, INFINITE);
+            DEBUG1 ("writer thread %p: got data to send", c->thread_hd );
+            LOCK (c->mutex);
+       	}
+        if ( c->stop_me ) {
+            UNLOCK (c->mutex);
+            break;
+        }
+        UNLOCK (c->mutex);
+
+        DEBUG2 ("writer thread %p: writing %d bytes",
+                c->thread_hd, c->nbytes );
+        if ( c->nbytes && !WriteFile ( c->file_hd,  c->buffer, c->nbytes,
+                                       &nwritten, NULL)) {
+            c->error_code = (int)GetLastError ();
+            c->error = 1;
+            DEBUG2 ("writer thread %p: write error: ec=%d",
+                    c->thread_hd, c->error_code );
+            break;
+        }
+        DEBUG2 ("writer thread %p: wrote %d bytes",
+                c->thread_hd, (int)nwritten );
+      
+        LOCK (c->mutex);
+        c->nbytes -= nwritten;
+        if (c->stop_me) {
+            UNLOCK (c->mutex);
+            break;
+        }
+        if ( !c->nbytes ) {
+            if ( !SetEvent (c->is_empty) )
+                DEBUG1 ("SetEvent failed: ec=%d", (int)GetLastError ());
+        }
+        UNLOCK (c->mutex);
+    }
+    /* indicate that we have an error  */
+    if ( !SetEvent (c->is_empty) )
+        DEBUG1 ("SetEvent failed: ec=%d", (int)GetLastError ());
+    DEBUG1 ("writer thread %p ended", c->thread_hd );
+    SetEvent (c->stopped);
+
+    return 0;
+}
+
+
+static struct writer_context_s *
+create_writer (HANDLE fd)
+{
+    struct writer_context_s *c;
+    SECURITY_ATTRIBUTES sec_attr;
+    DWORD tid;
+
+    DEBUG1 ("creating new write thread for file handle %p", fd );
+    memset (&sec_attr, 0, sizeof sec_attr );
+    sec_attr.nLength = sizeof sec_attr;
+    sec_attr.bInheritHandle = FALSE;
+
+    c = xtrycalloc (1, sizeof *c );
+    if (!c)
+        return NULL;
+
+    c->file_hd = fd;
+    c->have_data = CreateEvent (&sec_attr, FALSE, FALSE, NULL);
+    c->is_empty  = CreateEvent (&sec_attr, TRUE, TRUE, NULL);
+    c->stopped = CreateEvent (&sec_attr, TRUE, FALSE, NULL);
+    if (!c->have_data || !c->is_empty || !c->stopped ) {
+        DEBUG1 ("** CreateEvent failed: ec=%d\n", (int)GetLastError ());
+        if (c->have_data)
+            CloseHandle (c->have_data);
+        if (c->is_empty)
+            CloseHandle (c->is_empty);
+        if (c->stopped)
+            CloseHandle (c->stopped);
+        xfree (c);
+        return NULL;
+    }
+
+    c->is_empty = set_synchronize (c->is_empty);
+    INIT_LOCK (c->mutex);
+
+    c->thread_hd = CreateThread (&sec_attr, 0, writer, c, 0, &tid );
+    if (!c->thread_hd) {
+        DEBUG1 ("** failed to create writer thread: ec=%d\n",
+                 (int)GetLastError ());
+        DESTROY_LOCK (c->mutex);
+        if (c->have_data)
+            CloseHandle (c->have_data);
+        if (c->is_empty)
+            CloseHandle (c->is_empty);
+        if (c->stopped)
+            CloseHandle (c->stopped);
+        xfree (c);
+        return NULL;
+    }    
+
+    return c;
+}
+
+static void
+destroy_writer (struct writer_context_s *c)
+{
+    c->stop_me = 1;
+    if (c->have_data) 
+        SetEvent (c->have_data);
+
+    DEBUG1 ("waiting for thread %p termination ...", c->thread_hd );
+    WaitForSingleObject (c->stopped, INFINITE);
+    DEBUG1 ("thread %p has terminated", c->thread_hd );
+    
+    if (c->stopped)
+        CloseHandle (c->stopped);
+    if (c->have_data)
+        CloseHandle (c->have_data);
+    if (c->is_empty)
+        CloseHandle (c->is_empty);
+    CloseHandle (c->thread_hd);
+    DESTROY_LOCK (c->mutex);
+    xfree (c);
+}
+
+
+/* 
+ * Find a writer context or create a new one 
+ * Note that the writer context will last until a io_close.
+ */
+static struct writer_context_s *
+find_writer (int fd, int start_it)
+{
+    int i;
+
+    for (i=0; i < writer_table_size ; i++ ) {
+        if ( writer_table[i].used && writer_table[i].fd == fd )
+            return writer_table[i].context;
+    }
+    if (!start_it)
+        return NULL;
+
+    LOCK (writer_table_lock);
+    for (i=0; i < writer_table_size; i++ ) {
+        if (!writer_table[i].used) {
+            writer_table[i].fd = fd;
+            writer_table[i].context = create_writer (fd_to_handle (fd));
+            writer_table[i].used = 1;
+            UNLOCK (writer_table_lock);
+            return writer_table[i].context;
+        }
+    }
+    UNLOCK (writer_table_lock);
+    return NULL;
+}
+
+
+static void
+kill_writer (int fd)
+{
+    int i;
+
+    LOCK (writer_table_lock);
+    for (i=0; i < writer_table_size; i++ ) {
+        if (writer_table[i].used && writer_table[i].fd == fd ) {
+            destroy_writer (writer_table[i].context);
+            writer_table[i].context = NULL;
+            writer_table[i].used = 0;
+            break;
+        }
+    }
+    UNLOCK (writer_table_lock);
+}
+
+
+
+
 int
 _gpgme_io_write ( int fd, const void *buffer, size_t count )
 {
-    DWORD nwritten;
+    struct writer_context_s *c = find_writer (fd,1);
-    HANDLE h = fd_to_handle (fd);
-
-    /* writing blocks for large counts, so we limit it here. */
-    if (count > 1024)
-        count = 1024;
 
     DEBUG2 ("fd %d: about to write %d bytes\n", fd, (int)count );
-    if ( !WriteFile ( h, buffer, count, &nwritten, NULL) ) {
+    if ( !c ) {
-        DEBUG1 ("WriteFile failed: ec=%d\n", (int)GetLastError ());
+        DEBUG0 ( "no writer thread\n");
         return -1;
     }
-    DEBUG2 ("fd %d:          wrote %d bytes\n",
-                   fd, (int)nwritten );
 
-    return (int)nwritten;
+    LOCK (c->mutex);
+    if ( c->nbytes ) { /* bytes are pending for send */
+        UNLOCK (c->mutex);
+        DEBUG2 ("fd %d: waiting for empty buffer in thread %p",
+                fd, c->thread_hd);
+        WaitForSingleObject (c->is_empty, INFINITE);
+        DEBUG2 ("fd %d: thread %p buffer is empty", fd, c->thread_hd);
+        assert (!c->nbytes);
+        LOCK (c->mutex);
+    }
+    
+    if ( c->error) {
+        UNLOCK (c->mutex);
+        DEBUG1 ("fd %d: write error", fd );
+        return -1;
+    }
+      
+    if (count > WRITEBUF_SIZE)
+        count = WRITEBUF_SIZE;
+    memcpy (c->buffer, buffer, count);
+    c->nbytes = count;
+    if (!SetEvent (c->have_data))
+        DEBUG1 ("SetEvent failed: ec=%d", (int)GetLastError ());
+    UNLOCK (c->mutex);
+
+    DEBUG2 ("fd %d:         copied %d bytes\n",
+                   fd, (int)count );
+    return (int)count;
 }
 
+
 int
 _gpgme_io_pipe ( int filedes[2], int inherit_idx )
 {
@@ -448,6 +692,7 @@ _gpgme_io_close ( int fd )
 
     DEBUG1 ("** closing handle for fd %d\n", fd);
     kill_reader (fd);
+    kill_writer (fd);
     LOCK (notify_table_lock);
     for ( i=0; i < DIM (notify_table); i++ ) {
         if (notify_table[i].inuse && notify_table[i].fd == fd) {
@@ -736,13 +981,13 @@ _gpgme_io_select ( struct io_select_fd_s *fds, size_t nfds )
     HANDLE waitbuf[MAXIMUM_WAIT_OBJECTS];
     int    waitidx[MAXIMUM_WAIT_OBJECTS];
     int code, nwait;
-    int i, any, any_write;
+    int i, any;
     int count;
     void *dbg_help;
 
  restart:
     DEBUG_BEGIN (dbg_help, "select on [ ");
-    any = any_write = 0;
+    any = 0;
     nwait = 0;
     count = 0;
     for ( i=0; i < nfds; i++ ) {
@@ -772,13 +1017,22 @@ _gpgme_io_select ( struct io_select_fd_s *fds, size_t nfds )
                 any = 1;
             }
             else if ( fds[i].for_write ) {
+                struct writer_context_s *c = find_writer (fds[i].fd,1);
+                
+                if (!c) { 
+                    DEBUG1 ("oops: no writer thread for fd %d", fds[i].fd);
+                }
+                else {
+                    if ( nwait >= DIM (waitbuf) ) {
+                        DEBUG_END (dbg_help, "oops ]");
+                        DEBUG0 ("Too many objects for WFMO!" );
+                        return -1;
+                    }
+                    waitidx[nwait]   = i;
+                    waitbuf[nwait++] = c->is_empty;
+                }
                 DEBUG_ADD1 (dbg_help, "w%d ", fds[i].fd );
                 any = 1;
-                /* no way to see whether a handle is ready for writing,
-                 * so we signal them all */
-                fds[i].signaled = 1;
-                any_write =1;
-                count++;
             }
         }
     }
@@ -786,7 +1040,7 @@ _gpgme_io_select ( struct io_select_fd_s *fds, size_t nfds )
     if (!any) 
         return 0;
 
-    code = WaitForMultipleObjects ( nwait, waitbuf, 0, any_write? 200:1000);
+    code = WaitForMultipleObjects ( nwait, waitbuf, 0, 1000);
     if ( code >= WAIT_OBJECT_0 && code < WAIT_OBJECT_0 + nwait ) {
         /* This WFMO is a really silly function:  It does return either
          * the index of the signaled object or if 2 objects have been