closes #5182 Remove oldest_living_xid(and time) from engine status.

This cleans up some of the transaction manager code.
Optimize looks at the OMT now

git-svn-id: file:///svn/toku/tokudb@45202 c7de825b-a66e-492c-adef-691d508d4ae1

ft/ft-ops.c

@@ -2597,7 +2597,7 @@ toku_ft_optimize (FT_HANDLE brt) {
 
     TOKULOGGER logger = toku_cachefile_logger(brt->ft->cf);
     if (logger) {
-        TXNID oldest = toku_txn_manager_get_oldest_living_xid(logger->txn_manager, NULL);
+        TXNID oldest = toku_txn_manager_get_oldest_living_xid(logger->txn_manager);
 
         XIDS root_xids = xids_get_root_xids();
         XIDS message_xids;

ft/txn_manager.c

@@ -20,8 +20,6 @@ struct txn_manager {
     // Contains 3-tuples: (TXNID begin_id, TXNID end_id, uint64_t num_live_list_references)
     //                    for committed root transaction ids that are still referenced by a live list.
     OMT referenced_xids;
-    TXNID oldest_living_xid;
-    time_t oldest_living_starttime;   // timestamp in seconds of when txn with oldest_living_xid started
     struct toku_list prepared_txns; // transactions that have been prepared and are unresolved, but have not been returned through txn_recover.
     struct toku_list prepared_and_returned_txns; // transactions that have been prepared and unresolved, and have been returned through txn_recover.  We need this list so that we can restart the recovery.
 
@@ -29,28 +27,9 @@ struct txn_manager {
     TXNID last_xid;
 };
 
-static TXN_MANAGER_STATUS_S txn_manager_status;
 BOOL garbage_collection_debug = FALSE;
 
 
-#define STATUS_INIT(k,t,l) { \
-    txn_manager_status.status[k].keyname = #k; \
-    txn_manager_status.status[k].type    = t;  \
-    txn_manager_status.status[k].legend  = "txn: " l; \
-    }
-
-static void
-status_init(void) {
-    // Note, this function initializes the keyname, type, and legend fields.
-    // Value fields are initialized to zero by compiler.
-    STATUS_INIT(TXN_OLDEST_LIVE,      UINT64,   "xid of oldest live transaction");
-    STATUS_INIT(TXN_OLDEST_STARTTIME, UNIXTIME, "start time of oldest live transaction");
-    txn_manager_status.initialized = true;
-}
-#undef STATUS_INIT
-
-#define STATUS_VALUE(x) txn_manager_status.status[x].value.num
-
 static BOOL is_txnid_live(TXN_MANAGER txn_manager, TXNID txnid) {
     TOKUTXN result = NULL;
     toku_txn_manager_id2txn_unlocked(txn_manager, txnid, &result);
@@ -230,26 +209,6 @@ verify_snapshot_system(TXN_MANAGER txn_manager UU()) {
     }
 }
 
-static TXNID txn_manager_get_oldest_living_xid_unlocked(
-    TXN_MANAGER txn_manager, 
-    time_t * oldest_living_starttime
-    );
-
-void toku_txn_manager_get_status(TOKULOGGER logger, TXN_MANAGER_STATUS s) {
-    if (!txn_manager_status.initialized) {
-        status_init();
-    }
-    {
-        if (logger) {
-            time_t oldest_starttime;
-            STATUS_VALUE(TXN_OLDEST_LIVE) = txn_manager_get_oldest_living_xid_unlocked(logger->txn_manager, &oldest_starttime);
-            STATUS_VALUE(TXN_OLDEST_STARTTIME) = (uint64_t) oldest_starttime;
-        }
-    }
-    *s = txn_manager_status;
-}
-
-
 void toku_txn_manager_init(TXN_MANAGER* txn_managerp) {
     int r = 0;
     TXN_MANAGER XCALLOC(txn_manager);
@@ -262,8 +221,6 @@ void toku_txn_manager_init(TXN_MANAGER* txn_managerp) {
     assert_zero(r);
     r = toku_omt_create(&txn_manager->referenced_xids);
     assert_zero(r);
-    txn_manager->oldest_living_xid = TXNID_NONE_LIVING;
-    txn_manager->oldest_living_starttime = 0;
     txn_manager->last_xid = 0;
     toku_list_init(&txn_manager->prepared_txns);
     toku_list_init(&txn_manager->prepared_and_returned_txns);
@@ -282,23 +239,19 @@ void toku_txn_manager_destroy(TXN_MANAGER txn_manager) {
     toku_free(txn_manager);
 }
 
-static TXNID txn_manager_get_oldest_living_xid_unlocked(
-    TXN_MANAGER txn_manager,
-    time_t * oldest_living_starttime
-    )
-{
-    TXNID rval = 0;
-    rval = txn_manager->oldest_living_xid;
-    if (oldest_living_starttime) {
-        *oldest_living_starttime = txn_manager->oldest_living_starttime;
-    }
-    return rval;
-}
-
-TXNID toku_txn_manager_get_oldest_living_xid(TXN_MANAGER txn_manager, time_t * oldest_living_starttime) {
-    TXNID rval = 0;
+TXNID
+toku_txn_manager_get_oldest_living_xid(TXN_MANAGER txn_manager) {
+    TXNID rval = TXNID_NONE_LIVING;
     toku_mutex_lock(&txn_manager->txn_manager_lock);
-    rval = txn_manager_get_oldest_living_xid_unlocked(txn_manager, oldest_living_starttime);    
+    
+    if (toku_omt_size(txn_manager->live_root_txns) > 0) {
+        OMTVALUE txnidv;
+        // We use live_root_txns because roots are always older than children,
+        // and live_root_txns stores TXNIDs directly instead of TOKUTXNs in live_txns
+        int r = toku_omt_fetch(txn_manager->live_root_txns, 0, &txnidv);
+        invariant_zero(r);
+        rval = (TXNID)txnidv;
+    }
     toku_mutex_unlock(&txn_manager->txn_manager_lock);
     return rval;
 }
@@ -389,6 +342,7 @@ int toku_txn_manager_start_txn(
     }
     if (xid == TXNID_NONE) {
         invariant(!for_recovery);
+        // The transaction manager maintains the latest transaction id.
         xid = ++txn_manager->last_xid;
         invariant(logger);
     }
@@ -403,21 +357,6 @@ int toku_txn_manager_start_txn(
 
     toku_txn_update_xids_in_txn(txn, xid);
 
-    if (!for_recovery) {
-        // TODO(leif): this would be WRONG during recovery.  We cannot
-        // assume that the first xbegin we see is the oldest, because it's
-        // just the txn that *did a write* first.  Right now, this cached
-        // value is only used for engine status, so we're not too worried.
-        // Maybe we just kill this (txn_manager->oldest_living_*).  Also
-        // see comment on txn_manager_get_oldest_living_xid_unlocked.
-        if (toku_omt_size(txn_manager->live_txns) == 0) {
-            assert(txn_manager->oldest_living_xid == TXNID_NONE_LIVING);
-            txn_manager->oldest_living_xid = txn->txnid64;
-            txn_manager->oldest_living_starttime = txn->starttime;
-        }
-        assert(txn_manager->oldest_living_xid <= txn->txnid64);
-    }
-
     //Add txn to list (omt) of live transactions
     omt_insert_at_end_unless_recovery(txn_manager->live_txns, find_by_xid, txn, (OMTVALUE) txn, for_recovery);
 
@@ -638,25 +577,6 @@ void toku_txn_manager_finish_txn(TXN_MANAGER txn_manager, TOKUTXN txn) {
         }
     }
 
-    assert(txn_manager->oldest_living_xid <= txn->txnid64);
-    if (txn->txnid64 == txn_manager->oldest_living_xid) {
-        // oldest_living_xid is always zero during recovery
-        OMTVALUE oldest_txnv;
-        r = toku_omt_fetch(txn_manager->live_txns, 0, &oldest_txnv);
-        if (r==0) {
-            TOKUTXN oldest_txn = oldest_txnv;
-            assert(oldest_txn != txn); // We just removed it
-            assert(oldest_txn->txnid64 > txn_manager->oldest_living_xid); //Must be newer than the previous oldest
-            txn_manager->oldest_living_xid = oldest_txn->txnid64;
-            txn_manager->oldest_living_starttime = oldest_txn->starttime;
-        }
-        else {
-            //No living transactions
-            assert(r==EINVAL);
-            txn_manager->oldest_living_xid = TXNID_NONE_LIVING;
-            txn_manager->oldest_living_starttime = 0;
-        }
-    }
     if (garbage_collection_debug) {
         verify_snapshot_system(txn_manager);
     }
@@ -924,4 +844,3 @@ toku_txn_manager_increase_last_xid(TXN_MANAGER mgr, uint64_t increment) {
     toku_mutex_unlock(&mgr->txn_manager_lock);
 }
 
-#undef STATUS_VALUE

ft/txn_manager.h

@@ -13,25 +13,10 @@ extern "C" {
 
 struct txn_manager;
 
-typedef enum {
-    TXN_OLDEST_LIVE,       // xid of oldest live transaction
-    TXN_OLDEST_STARTTIME,  // start time of oldest live txn
-    TXN_MANAGER_STATUS_NUM_ROWS
-} txn_manager_status_entry;
-
-typedef struct {
-    BOOL initialized;
-    TOKU_ENGINE_STATUS_ROW_S status[TXN_MANAGER_STATUS_NUM_ROWS];
-} TXN_MANAGER_STATUS_S, *TXN_MANAGER_STATUS;
-
-
-
-void toku_txn_manager_get_status(TOKULOGGER logger, TXN_MANAGER_STATUS s);
-
 void toku_txn_manager_init(TXN_MANAGER* txn_manager);
 void toku_txn_manager_destroy(TXN_MANAGER txn_manager);
 
-TXNID toku_txn_manager_get_oldest_living_xid(TXN_MANAGER txn_manager, time_t * oldest_living_starttime);
+TXNID toku_txn_manager_get_oldest_living_xid(TXN_MANAGER txn_manager);
 
 // Assign a txnid. Log the txn begin in the recovery log. Initialize the txn live lists.
 // Also, create the txn.

src/ydb.c

@@ -1810,7 +1810,6 @@ env_get_engine_status_num_rows (DB_ENV * UU(env), uint64_t * num_rowsp) {
     num_rows += FT_FLUSHER_STATUS_NUM_ROWS;
     num_rows += FT_HOT_STATUS_NUM_ROWS;
     num_rows += TXN_STATUS_NUM_ROWS;
-    num_rows += TXN_MANAGER_STATUS_NUM_ROWS;
     num_rows += LOGGER_STATUS_NUM_ROWS;
     num_rows += MEMORY_STATUS_NUM_ROWS;
     num_rows += FS_STATUS_NUM_ROWS;
@@ -1930,13 +1929,6 @@ env_get_engine_status (DB_ENV * env, TOKU_ENGINE_STATUS_ROW engstat, uint64_t ma
                 engstat[row++] = txnstat.status[i];
             }
         }
-        {
-            TXN_MANAGER_STATUS_S txn_manager_stat;
-            toku_txn_manager_get_status(env->i->logger, &txn_manager_stat);
-            for (int i = 0; i < TXN_MANAGER_STATUS_NUM_ROWS && row < maxrows; i++) {
-                engstat[row++] = txn_manager_stat.status[i];
-            }
-        }
         {
             LOGGER_STATUS_S loggerstat;
             toku_logger_get_status(env->i->logger, &loggerstat);