From 4072f162b426d2e250d4b95d55e81b6908b8b509 Mon Sep 17 00:00:00 2001
From: erdgeist <>
Date: Wed, 21 Nov 2007 01:55:15 +0000
Subject: [PATCH] Make sync generation multithreaded.

---
 ot_sync.c | 121 ++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 90 insertions(+), 31 deletions(-)

diff --git a/ot_sync.c b/ot_sync.c
index 6e95a98..5261ee6 100644
--- a/ot_sync.c
+++ b/ot_sync.c
@@ -6,6 +6,7 @@
 #include <sys/mman.h>
 #include <stdio.h>
 #include <string.h>
+#include <pthread.h>
 
 /* Libowfat */
 #include "scan.h"
@@ -17,6 +18,9 @@
 #include "ot_sync.h"
 
 #ifdef WANT_TRACKER_SYNC
+
+#define OT_SYNC_CHUNK_SIZE (512*1024)
+
 /* Import Changeset from an external authority
    format: d4:syncd[..]ee
    [..]:   ( 20:01234567890abcdefghij16:XXXXYYYY )+
@@ -60,48 +64,103 @@ int add_changeset_to_tracker( ot_byte *data, size_t len ) {
 /* Proposed output format
    d4:syncd20:<info_hash>8*N:(xxxxyyyy)*Nee
 */
-size_t return_changeset_for_tracker( char **reply ) {
-  size_t allocated = 0, i, replysize;
-  ot_vector *torrents_list;
+static void sync_make( int *iovec_entries, struct iovec **iovector ) {
   int    bucket;
-  char   *r;
+  char  *r, *re;
 
-  /* Maybe there is time to clean_all_torrents(); */
+  /* Setup return vector... */
+  *iovec_entries = 0;
+  *iovector = NULL;
+  if( !( r = iovec_increase( iovec_entries, iovector, OT_SYNC_CHUNK_SIZE ) ) )
+    return;
 
-  /* Determine space needed for whole changeset */
-  for( bucket = 0; bucket < OT_BUCKET_COUNT; ++bucket ) {
-    torrents_list = mutex_bucket_lock(bucket);
-    for( i=0; i<torrents_list->size; ++i ) {
-      ot_torrent *torrent = ((ot_torrent*)(torrents_list->data)) + i;
-      allocated += sizeof( ot_hash ) + sizeof(ot_peer) * torrent->peer_list->changeset.size + 13;
-    }
-    mutex_bucket_unlock(bucket);
-  }
+  /* ... and pointer to end of current output buffer.
+     This works as a low watermark */
+  re = r + OT_SYNC_CHUNK_SIZE;
 
-  /* add "d4:syncd" and "ee" */
-  allocated += 8 + 2;
+  memmove( r, "d4:syncd", 8 ); r += 8;
 
-  if( !( r = *reply = mmap( NULL, allocated, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0 ) ) )
-    return 0;
+  /* For each bucket... */
+  for( bucket=0; bucket<OT_BUCKET_COUNT; ++bucket ) {
+    /* Get exclusive access to that bucket */
+    ot_vector *torrents_list = mutex_bucket_lock( bucket );
+    size_t tor_offset;
+
+    /* For each torrent in this bucket.. */
+    for( tor_offset=0; tor_offset<torrents_list->size; ++tor_offset ) {
+      /* Address torrents members */
+      ot_peerlist *peer_list = ( ((ot_torrent*)(torrents_list->data))[tor_offset] ).peer_list;
+      ot_hash     *hash      =&( ((ot_torrent*)(torrents_list->data))[tor_offset] ).hash;
+      const size_t byte_count = sizeof(ot_peer) * peer_list->changeset.size;
+
+      /* If we reached our low watermark in buffer... */
+      if( re - r <= (ssize_t)(/* strlen( "20:" ) == */ 3 + sizeof( ot_hash ) + /* strlen_max( "%zd" ) == */ 12 + byte_count ) ) {
+
+        /* crop current output buffer to the amount really used */
+        iovec_fixlast( iovec_entries, iovector, OT_SYNC_CHUNK_SIZE - ( re - r ) );
+
+        /* And allocate a fresh output buffer at the end of our buffers list */
+        if( !( r = iovec_increase( iovec_entries, iovector, OT_SYNC_CHUNK_SIZE ) ) ) {
+
+          /* If this fails: free buffers */
+          iovec_free( iovec_entries, iovector );
+
+          /* Release lock on current bucket and return */
+          mutex_bucket_unlock( bucket );
+          return;
+        }
+
+        /* Adjust new end of output buffer */
+        re = r + OT_SYNC_CHUNK_SIZE;
+      }
 
-  memmove( r, "d4:syncd", 8 ); r += 8;
-  for( bucket = 0; bucket < OT_BUCKET_COUNT; ++bucket ) {
-    torrents_list = mutex_bucket_lock(bucket);
-    for( i=0; i<torrents_list->size; ++i ) {
-      ot_torrent *torrent = ((ot_torrent*)(torrents_list->data)) + i;
-      const size_t byte_count = sizeof(ot_peer) * torrent->peer_list->changeset.size;
       *r++ = '2'; *r++ = '0'; *r++ = ':';
-      memmove( r, torrent->hash, sizeof( ot_hash ) ); r += sizeof( ot_hash );
+      memmove( r, hash, sizeof( ot_hash ) ); r += sizeof( ot_hash );
       r += sprintf( r, "%zd:", byte_count );
-      memmove( r, torrent->peer_list->changeset.data, byte_count ); r += byte_count;
+      memmove( r, peer_list->changeset.data, byte_count ); r += byte_count;
     }
-    mutex_bucket_unlock(bucket);
+
+    /* All torrents done: release lock on currenct bucket */
+    mutex_bucket_unlock( bucket );
   }
-  *r++ = 'e'; *r++ = 'e';
 
-  replysize = ( r - *reply );
-  fix_mmapallocation( *reply, allocated, replysize );
+  /* Close bencoded sync dictionary */
+  *r++='e'; *r++='e';
 
-  return replysize;
+  /* Release unused memory in current output buffer */
+  iovec_fixlast( iovec_entries, iovector, OT_SYNC_CHUNK_SIZE - ( re - r ) );
 }
+
+/* This is the entry point into this worker thread
+   It grabs tasks from mutex_tasklist and delivers results back
+*/
+static void * sync_worker( void * args) {
+  int iovec_entries;
+  struct iovec *iovector;
+
+  args = args;
+
+  while( 1 ) {
+    ot_tasktype tasktype = TASK_SYNC_OUT;
+    ot_taskid   taskid   = mutex_workqueue_poptask( &tasktype );
+    sync_make( &iovec_entries, &iovector );
+    if( mutex_workqueue_pushresult( taskid, iovec_entries, iovector ) )
+      iovec_free( &iovec_entries, &iovector );
+  }
+  return NULL;
+}
+
+static pthread_t thread_id;
+void sync_init( ) {
+  pthread_create( &thread_id, NULL, sync_worker, NULL );
+}
+
+void sync_deinit( ) {
+  pthread_cancel( thread_id );
+}
+
+void sync_deliver( int64 socket ) {
+  mutex_workqueue_pushtask( socket, TASK_SYNC_OUT );
+}
+
 #endif