# HG changeset patch
# User jbe
# Date 1428507811 -7200
# Node ID 4f9e4c6109f46e904d87d6c30feb0796d65edfb4
# Parent  51ff6ad11677d342361b88df6914231fd0f179e5
Different buffering model for I/O writer

diff -r 51ff6ad11677 -r 4f9e4c6109f4 moonbridge_io.c
--- a/moonbridge_io.c	Wed Apr 08 05:26:15 2015 +0200
+++ b/moonbridge_io.c	Wed Apr 08 17:43:31 2015 +0200
@@ -46,7 +46,8 @@
   int writeqout;
 #endif
   size_t writeqoff;
-  int writebufcnt;
+  int writebufin;
+  int writebufout;
   char readbuf[MOONBR_IO_READBUFLEN];
   char writebuf[MOONBR_IO_WRITEBUFLEN];
 } moonbr_io_handle_t;
@@ -126,7 +127,7 @@
   size_t luabufcnt = 0;
   int endcnt;
   char *terminatorpos;
-  ssize_t result;
+  ssize_t bytesread;
   handle = luaL_checkudata(L, 1, MOONBR_IO_HANDLE_MT_REGKEY);
   maxread = luaL_optinteger(L, 2, 0);
   terminatorstr = luaL_optlstring(L, 3, "", &terminatorlen);
@@ -168,17 +169,17 @@
     luabufcnt += handle->readbufcnt;
     handle->readbufcnt = 0;
     do {
-      result = read(handle->fd, handle->readbuf, MOONBR_IO_READBUFLEN);
-    } while (result < 0 && (errno == EINTR));
-    if (result == 0 || (nonblocking && result < 0 && (errno == EAGAIN || errno == EWOULDBLOCK))) break;
-    if (result < 0) {
+      bytesread = read(handle->fd, handle->readbuf, MOONBR_IO_READBUFLEN);
+    } while (bytesread < 0 && (errno == EINTR));
+    if (bytesread == 0 || (nonblocking && bytesread < 0 && (errno == EAGAIN || errno == EWOULDBLOCK))) break;
+    if (bytesread < 0) {
       moonbr_io_errmsg();
       handle->readerr = 1;
       lua_pushnil(L);
       lua_pushstring(L, errmsg);
       return 2;
     }
-    handle->readbufcnt += result;
+    handle->readbufcnt += bytesread;
   }
   if (!drain) {
     luaL_addlstring(&luabuf, handle->readbuf, handle->readbufcnt);
@@ -187,14 +188,14 @@
   luabufcnt += handle->readbufcnt;
   handle->readbufcnt = 0;
   if (!drain) {
-    if (!luabufcnt && result == 0) {
+    if (!luabufcnt && bytesread == 0) {
       moonbr_io_read_impl_eof:
       lua_pushboolean(L, 0);
       lua_pushliteral(L, "End of file");
       return 2;
     }
   } else {
-    if (!luabufcnt && result == 0) lua_pushboolean(L, 1);
+    if (!luabufcnt && bytesread == 0) lua_pushboolean(L, 1);
     else lua_pushboolean(L, luabufcnt);
   }
   return 1;
@@ -221,8 +222,7 @@
   int i, top;
   const char *str;
   size_t strlen;
-  size_t written;
-  ssize_t result;
+  ssize_t written;
   handle = luaL_checkudata(L, 1, MOONBR_IO_HANDLE_MT_REGKEY);
   if (handle->closed) luaL_error(L, "Attempt to write to a closed I/O handle");
   if (handle->finished) luaL_error(L, "Attempt to write to a finished I/O handle");
@@ -231,10 +231,11 @@
     lua_pushliteral(L, "Previous write error");
     return 2;
   }
+  handle->writeerr = 1;
   moonbr_io_handle_set_nonblocking(L, handle, nonblocking);
   top = lua_gettop(L);
   lua_getuservalue(L, 1);
-  lua_getfield(L, -1, "writebuf");
+  lua_getfield(L, -1, "writequeue");
   for (i=2; i<=top; i++) {
     luaL_checklstring(L, i, &strlen);
     lua_pushvalue(L, i);
@@ -245,39 +246,48 @@
     lua_rawgeti(L, -1, handle->writeqout);
     str = lua_tolstring(L, -1, &strlen);
     while (handle->writeqoff < strlen) {
-      if (strlen - handle->writeqoff <= MOONBR_IO_WRITEBUFLEN - handle->writebufcnt) {
-        memcpy(handle->writebuf + handle->writebufcnt, str + handle->writeqoff, strlen - handle->writeqoff);
-        handle->writebufcnt += strlen - handle->writeqoff;
+      if (
+        strlen - handle->writeqoff <=
+        MOONBR_IO_WRITEBUFLEN - handle->writebufin
+      ) {
+        memcpy(
+          handle->writebuf + handle->writebufin,
+          str + handle->writeqoff,
+          strlen - handle->writeqoff
+        );
+        handle->writebufin += strlen - handle->writeqoff;
         break;
       } else {
         moonbr_io_handle_set_nopush(L, handle, 1);
-        written = 0;
-        memcpy(handle->writebuf + handle->writebufcnt, str + handle->writeqoff, MOONBR_IO_WRITEBUFLEN - handle->writebufcnt);
-        handle->writeqoff += MOONBR_IO_WRITEBUFLEN - handle->writebufcnt;
-        while (written < MOONBR_IO_WRITEBUFLEN) {
-          result = write(handle->fd, handle->writebuf + written, MOONBR_IO_WRITEBUFLEN - written);
-          if (result < 0) {
+        memcpy(
+          handle->writebuf + handle->writebufin,
+          str + handle->writeqoff,
+          MOONBR_IO_WRITEBUFLEN - handle->writebufin
+        );
+        handle->writeqoff += MOONBR_IO_WRITEBUFLEN - handle->writebufin;
+        while (handle->writebufout < MOONBR_IO_WRITEBUFLEN) {
+          written = write(
+            handle->fd,
+            handle->writebuf + handle->writebufout,
+            MOONBR_IO_WRITEBUFLEN - handle->writebufout
+          );
+          if (written < 0) {
             if (nonblocking && (errno == EAGAIN || errno == EWOULDBLOCK)) {
-              if (written) {
-                handle->writebufcnt -= written;
-                memmove(handle->writebuf, handle->writebuf + written, handle->writebufcnt);
-                goto moonbr_io_write_impl_continue;
-              }
               goto moonbr_io_write_impl_block;
             } else if (errno != EINTR) {
               moonbr_io_errmsg();
-              handle->writeerr = 1;
               lua_pushnil(L);
               lua_pushstring(L, errmsg);
               return 2;
             }
+          } else {
+            handle->writebufout += written;
+            handle->writeleft -= written;
           }
-          written += result;
-          handle->writeleft -= result;
         }
-        handle->writebufcnt = 0;
+        handle->writebufin = 0;
+        handle->writebufout = 0;
       }
-      moonbr_io_write_impl_continue:;
     }
     handle->writeqoff = 0;
     lua_pop(L, 1);
@@ -286,37 +296,36 @@
   }
   if (flush) {
     moonbr_io_handle_set_nopush(L, handle, 0);
-    written = 0;
-    while (written < handle->writebufcnt) {
-      result = write(handle->fd, handle->writebuf + written, handle->writebufcnt - written);
-      if (result < 0) {
+    while (handle->writebufout < handle->writebufin) {
+      written = write(
+        handle->fd,
+        handle->writebuf + handle->writebufout,
+        handle->writebufin - handle->writebufout
+      );
+      if (written < 0) {
         if (nonblocking && (errno == EAGAIN || errno == EWOULDBLOCK)) {
-          if (written) {
-            handle->writebufcnt -= written;
-            memmove(handle->writebuf, handle->writebuf + written, handle->writebufcnt);
-          }
           goto moonbr_io_write_impl_block;
         } else if (errno != EINTR) {
           moonbr_io_errmsg();
-          handle->writeerr = -1;
           lua_pushnil(L);
           lua_pushstring(L, errmsg);
           return 2;
         }
       } else {
-        written += result;
-        handle->writeleft -= result;
+        handle->writebufout += written;
+        handle->writeleft -= written;
       }
     }
-    handle->writebufcnt = 0;
-    if (nonblocking) lua_pushinteger(L, 0);
-  } else {
-    if (nonblocking) lua_pushinteger(L, handle->writeleft);
+    handle->writebufin = 0;
+    handle->writebufout = 0;
   }
-  if (!nonblocking) lua_pushvalue(L, 1);
+  if (nonblocking) lua_pushinteger(L, 0);
+  else lua_pushvalue(L, 1);
+  handle->writeerr = 0;
   return 1;
   moonbr_io_write_impl_block:
   lua_pushinteger(L, handle->writeleft);
+  handle->writeerr = 0;
   return 1;
 }
 
@@ -450,13 +459,14 @@
   handle->writeqin = 0;
   handle->writeqout = 0;
   handle->writeqoff = 0;
-  handle->writebufcnt = 0;
+  handle->writebufin = 0;
+  handle->writebufout = 0;
   moonbr_io_handle_set_linger(L, handle, 0);
   luaL_getmetatable(L, MOONBR_IO_HANDLE_MT_REGKEY);
   lua_setmetatable(L, -2);
   lua_newtable(L);  // uservalue
   lua_newtable(L);
-  lua_setfield(L, -2, "writebuf");
+  lua_setfield(L, -2, "writequeue");
   lua_newtable(L);  // public
   luaL_getmetatable(L, MOONBR_IO_HANDLE_PUBLIC_MT_REGKEY);
   lua_setmetatable(L, -2);