- file upload handler:

Do first read from socket before opening the disk file
    (an attempt to fix filesystem lockups on WCG).
    Increase buffer size from 16KB to 256KB.


svn path=/trunk/boinc/; revision=26046

checkin_notes

@@ -5593,7 +5593,7 @@ David  17 Aug 2012
         vda_lib2.cpp
         vda_lib.h
 
-David  17 Aug 2012
+David  18 Aug 2012
     - client: if a project has excluded GPUs of a given type,
         allow it to fetch work of that type if the # of runnable
         jobs it <= the # of non-excluded instances (rather than 0).
@@ -5601,3 +5601,12 @@ David  17 Aug 2012
     client/
         work_fetch.cpp,h
         rr_sim.cpp
+
+David  18 Aug 2012
+    - file upload handler:
+        Do first read from socket before opening the disk file
+        (an attempt to fix filesystem lockups on WCG).
+        Increase buffer size from 16KB to 256KB.
+
+    sched/
+        file_upload_handler.cpp

sched/file_upload_handler.cpp

@@ -105,7 +105,7 @@ int return_success(const char* text) {
     return 0;
 }
 
-#define BLOCK_SIZE  16382
+#define BLOCK_SIZE  (256*1024)
 double bytes_left=-1;
 
 // read from socket, write to file
@@ -114,9 +114,27 @@ double bytes_left=-1;
 int copy_socket_to_file(FILE* in, char* path, double offset, double nbytes) {
     unsigned char buf[BLOCK_SIZE];
     struct stat sbuf;
-    int pid;
+    int pid, fd=0;
 
-    // open file.  Use raw IO not buffered IO so that we can use reliable
+    // caller guarantees that nbytes > offset
+    //
+    bytes_left = nbytes - offset;
+
+    while (bytes_left > 0) {
+
+        int n, m, to_write;
+
+        m = bytes_left<(double)BLOCK_SIZE ? (int)bytes_left : BLOCK_SIZE;
+
+        // try to get m bytes from socket (n>=0 is number actually returned)
+        //
+        n = fread(buf, 1, m, in);
+
+        // delay opening the file until we've done the first socket read
+        // to avoid filesystem lockups (WCG, possible paranoia)
+        //
+        if (!fd) {
+            // Use raw IO not buffered IO so that we can use reliable
             // posix file locking.
             // Advisory file locking is not guaranteed reliable when
             // used with stream buffered IO.
@@ -172,20 +190,7 @@ int copy_socket_to_file(FILE* in, char* path, double offset, double nbytes) {
                      this_filename, (int)sbuf.st_size, offset
                 );
             }
-
-    // caller guarantees that nbytes > offset
-    //
-    bytes_left = nbytes - offset;
-
-    while (bytes_left > 0) {
-
-        int n, m, to_write;
-
-        m = bytes_left<(double)BLOCK_SIZE ? (int)bytes_left : BLOCK_SIZE;
-
-        // try to get m bytes from socket (n>=0 is number actually returned)
-        //
-        n = fread(buf, 1, m, in);
+        }
 
         // try to write n bytes to file
         //