perf: lookup tables for faster torrent searching. (#1778)

* perf: lookup tables for faster torrent searching.

tr_torrentFindFromId(), tr_torrentFindFromHashString(), and
tr_torrentFindFromHash() are now O(log N) instead of O(N) where
N is the number of torrents.

* build: fix clang-tidy warning

error: integer to pointer cast pessimizes optimization opportunities
[performance-no-int-to-ptr,-warnings-as-errors] from TR_BAD_SYS_FILE
which expands to INVALID_HANDLE_VALUE ((HANDLE)(LONG_PTR)-1)

libtransmission/session.c

@@ -43,6 +43,7 @@
 #include "platform.h" /* tr_lock, tr_getTorrentDir() */
 #include "platform-quota.h" /* tr_device_info_free() */
 #include "port-forwarding.h"
+#include "ptrarray.h"
 #include "rpc-server.h"
 #include "session.h"
 #include "session-id.h"
@@ -635,6 +636,9 @@ tr_session* tr_sessionInit(char const* configDir, bool messageQueuingEnabled, tr
     session->cache = tr_cacheNew(1024 * 1024 * 2);
     session->magicNumber = SESSION_MAGIC_NUMBER;
     session->session_id = tr_session_id_new();
+    session->torrentsSortedByHash = TR_PTR_ARRAY_INIT;
+    session->torrentsSortedByHashString = TR_PTR_ARRAY_INIT;
+    session->torrentsSortedById = TR_PTR_ARRAY_INIT;
     tr_bandwidthConstruct(&session->bandwidth, session, NULL);
     tr_variantInitList(&session->removedTorrents, 0);
 
@@ -2137,6 +2141,9 @@ void tr_sessionClose(tr_session* session)
     }
 
     tr_device_info_free(session->downloadDir);
+    tr_ptrArrayDestruct(&session->torrentsSortedByHash, NULL);
+    tr_ptrArrayDestruct(&session->torrentsSortedByHashString, NULL);
+    tr_ptrArrayDestruct(&session->torrentsSortedById, NULL);
     tr_free(session->torrentDoneScript);
     tr_free(session->configDir);
     tr_free(session->resumeDir);
@@ -3117,3 +3124,68 @@ int tr_sessionCountQueueFreeSlots(tr_session* session, tr_direction dir)
 
     return max - active_count;
 }
+
+static int compareTorrentsById(void const* va, void const* vb)
+{
+    tr_torrent const* const a = va;
+    tr_torrent const* const b = vb;
+    return a->uniqueId - b->uniqueId;
+}
+
+static int compareTorrentsByHashString(void const* va, void const* vb)
+{
+    tr_torrent const* const a = va;
+    tr_torrent const* const b = vb;
+    return evutil_ascii_strcasecmp(a->info.hashString, b->info.hashString);
+}
+
+static int compareTorrentsByHash(void const* va, void const* vb)
+{
+    tr_torrent const* const a = va;
+    tr_torrent const* const b = vb;
+    return memcmp(a->info.hash, b->info.hash, SHA_DIGEST_LENGTH);
+}
+
+void tr_sessionAddTorrent(tr_session* session, tr_torrent* tor)
+{
+    /* add tor to tr_session.torrentList */
+    tor->next = session->torrentList;
+    session->torrentList = tor;
+
+    /* add tor to tr_session.torrentsSortedByFoo */
+    tr_ptrArrayInsertSorted(&session->torrentsSortedById, tor, compareTorrentsById);
+    tr_ptrArrayInsertSorted(&session->torrentsSortedByHashString, tor, compareTorrentsByHashString);
+    tr_ptrArrayInsertSorted(&session->torrentsSortedByHash, tor, compareTorrentsByHash);
+
+    /* increment the torrent count */
+    ++session->torrentCount;
+}
+
+void tr_sessionRemoveTorrent(tr_session* session, tr_torrent* tor)
+{
+    /* remove tor from tr_session.torrentList */
+    if (tor == session->torrentList)
+    {
+        session->torrentList = tor->next;
+    }
+    else
+    {
+        for (tr_torrent* t = session->torrentList; t != NULL; t = t->next)
+        {
+            if (t->next == tor)
+            {
+                t->next = tor->next;
+                break;
+            }
+        }
+    }
+
+    /* remove tor from tr_session.torrentsSortedByFoo */
+    tr_ptrArrayRemoveSortedPointer(&session->torrentsSortedById, tor, compareTorrentsById);
+    tr_ptrArrayRemoveSortedPointer(&session->torrentsSortedByHashString, tor, compareTorrentsByHashString);
+    tr_ptrArrayRemoveSortedPointer(&session->torrentsSortedByHash, tor, compareTorrentsByHash);
+
+    /* decrement the torrent count */
+    TR_ASSERT(session->torrentCount >= 1);
+    session->torrentCount--;
+}

libtransmission/session.h

@@ -17,6 +17,7 @@
 #include "bandwidth.h"
 #include "bitfield.h"
 #include "net.h"
+#include "ptrarray.h"
 #include "tr-macros.h"
 #include "utils.h"
 #include "variant.h"
@@ -177,6 +178,9 @@ struct tr_session
 
     int torrentCount;
     tr_torrent* torrentList;
+    tr_ptrArray torrentsSortedByHash;
+    tr_ptrArray torrentsSortedByHashString;
+    tr_ptrArray torrentsSortedById;
 
     char* torrentDoneScript;
 
@@ -322,4 +326,7 @@ void tr_sessionGetNextQueuedTorrents(tr_session* session, tr_direction dir, size
 
 int tr_sessionCountQueueFreeSlots(tr_session* session, tr_direction);
 
+void tr_sessionAddTorrent(tr_session* session, tr_torrent* tor);
+void tr_sessionRemoveTorrent(tr_session* session, tr_torrent* tor);
+
 TR_END_DECLS

libtransmission/torrent.c

@@ -73,49 +73,40 @@ int tr_torrentId(tr_torrent const* tor)
     return tor != NULL ? tor->uniqueId : -1;
 }
 
+static int compareKeyToTorrentId(void const* va, void const* vb)
+{
+    tr_torrent const* const a = va;
+    int const b = *(int const*)vb;
+    return a->uniqueId - b;
+}
+
 tr_torrent* tr_torrentFindFromId(tr_session* session, int id)
 {
-    tr_torrent* tor = NULL;
+    return tr_ptrArrayFindSorted(&session->torrentsSortedById, &id, compareKeyToTorrentId);
+}
 
-    while ((tor = tr_torrentNext(session, tor)) != NULL)
+static int compareKeyToTorrentHashString(void const* va, void const* vb)
-    {
+{
-        if (tor->uniqueId == id)
+    tr_torrent const* const a = va;
-        {
+    char const* const b = vb;
-            return tor;
+    return evutil_ascii_strcasecmp(a->info.hashString, b);
-        }
-    }
-
-    return NULL;
 }
 
 tr_torrent* tr_torrentFindFromHashString(tr_session* session, char const* str)
 {
-    tr_torrent* tor = NULL;
+    return tr_ptrArrayFindSorted(&session->torrentsSortedByHashString, str, compareKeyToTorrentHashString);
+}
 
-    while ((tor = tr_torrentNext(session, tor)) != NULL)
+static int compareKeyToTorrentHash(void const* va, void const* vb)
-    {
+{
-        if (evutil_ascii_strcasecmp(str, tor->info.hashString) == 0)
+    tr_torrent const* const a = va;
-        {
+    uint8_t const* const b = vb;
-            return tor;
+    return memcmp(a->info.hash, b, SHA_DIGEST_LENGTH);
-        }
-    }
-
-    return NULL;
 }
 
 tr_torrent* tr_torrentFindFromHash(tr_session* session, uint8_t const* torrentHash)
 {
-    tr_torrent* tor = NULL;
+    return tr_ptrArrayFindSorted(&session->torrentsSortedByHash, torrentHash, compareKeyToTorrentHash);
-
-    while ((tor = tr_torrentNext(session, tor)) != NULL)
-    {
-        if ((*tor->info.hash == *torrentHash) && (memcmp(tor->info.hash, torrentHash, SHA_DIGEST_LENGTH) == 0))
-        {
-            return tor;
-        }
-    }
-
-    return NULL;
 }
 
 tr_torrent* tr_torrentFindFromMagnetLink(tr_session* session, char const* magnet)
@@ -975,24 +966,7 @@ static void torrentInit(tr_torrent* tor, tr_ctor const* ctor)
         tr_torrentSetIdleLimit(tor, tr_sessionGetIdleLimit(tor->session));
     }
 
-    /* add the torrent to tr_session.torrentList */
+    tr_sessionAddTorrent(session, tor);
-    session->torrentCount++;
-
-    if (session->torrentList == NULL)
-    {
-        session->torrentList = tor;
-    }
-    else
-    {
-        tr_torrent* it = session->torrentList;
-
-        while (it->next != NULL)
-        {
-            it = it->next;
-        }
-
-        it->next = tor;
-    }
 
     /* if we don't have a local .torrent file already, assume the torrent is new */
     isNewTorrent = !tr_sys_path_exists(tor->info.torrent, NULL);
@@ -1689,25 +1663,7 @@ static void freeTorrent(tr_torrent* tor)
     tr_free(tor->downloadDir);
     tr_free(tor->incompleteDir);
 
-    if (tor == session->torrentList)
+    tr_sessionRemoveTorrent(session, tor);
-    {
-        session->torrentList = tor->next;
-    }
-    else
-    {
-        for (tr_torrent* t = session->torrentList; t != NULL; t = t->next)
-        {
-            if (t->next == tor)
-            {
-                t->next = tor->next;
-                break;
-            }
-        }
-    }
-
-    /* decrement the torrent count */
-    TR_ASSERT(session->torrentCount >= 1);
-    session->torrentCount--;
 
     /* resequence the queue positions */
     tr_torrent* t = NULL;

tests/libtransmission/.clang-tidy

@@ -50,6 +50,7 @@ Checks: >
   -modernize-concat-nested-namespaces,
   -modernize-use-trailing-return-type,
   performance-*,
+  -performance-no-int-to-ptr,
   readability-*,
   -readability-convert-member-functions-to-static,
   -readability-function-cognitive-complexity,