performance enhancement

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@4639 57a11ea4-9604-0410-9ed3-97b8803252fd

src/engine/Account.c

@@ -109,6 +109,7 @@ xaccInitAccount (Account * acc)
   acc->splits      = NULL;
 
   acc->version = 0;
+  acc->version_check = 0;
   acc->editlevel = 0;
   acc->balance_dirty = FALSE;
   acc->sort_dirty = FALSE;

src/engine/AccountP.h

@@ -141,6 +141,7 @@ struct _account {
 
   /* version number, used for tracking multiuser updates */
   gint32 version;
+  guint32  version_check;  /* data aging timestamp */
 
   GList *splits;           /* list of split pointers */
 

src/engine/Transaction.c

@@ -666,6 +666,7 @@ xaccInitTransaction (Transaction * trans)
   trans->date_posted.tv_nsec = 0;
 
   trans->version = 0;
+  trans->version_check = 0;
   trans->marker = 0;
   trans->editlevel = 0;
   trans->do_free = FALSE;

src/engine/TransactionP.h

@@ -173,6 +173,7 @@ struct _transaction
 
   /* version number, used for tracking multiuser updates */
   gint32 version;
+  guint32 version_check; /* data aging timestamp */
 
   GList * splits; /* list of splits */
 

src/engine/gnc-pricedb-p.h

@@ -40,6 +40,7 @@ struct _GNCPrice {
   char *type;
   gnc_numeric value;
   gint32   version;              /* version number, for syncing with backend */
+  guint32  version_check;        /* data aging timestamp */
 
   /* 'private' object management fields */
   guint32  refcount;             /* garbage collection reference count */

src/engine/gnc-pricedb.c

@@ -58,6 +58,7 @@ gnc_price_create(void)
   p->not_saved = FALSE;
   p->do_free = FALSE;
   p->version = 0;
+  p->version_check = 0;
   xaccGUIDNew (&p->guid);
   xaccStoreEntity(p, &p->guid, GNC_ID_PRICE); 
   gnc_engine_generate_event (&p->guid, GNC_EVENT_CREATE);

src/engine/sql/PostgresBackend.c

@@ -446,8 +446,9 @@ pgendRunQuery (Backend *bend, Query *q)
    sqlQuery *sq;
    GList *node, *anode, *xaction_list= NULL, *acct_list = NULL;
 
-   ENTER (" ");
+   ENTER ("be=%p, qry=%p", be, q);
    if (!be || !q) return;
+   be->version_check = (guint32) time(0);
 
    gnc_engine_suspend_events();
    pgendDisable(be);
@@ -564,6 +565,8 @@ pgendSync (Backend *bend, AccountGroup *grp)
    PGBackend *be = (PGBackend *)bend;
    ENTER ("be=%p, grp=%p", be, grp);
 
+   be->version_check = (guint32) time(0);
+
    /* store the account group hierarchy, and then all transactions */
    pgendStoreGroup (be, grp);
    pgendStoreAllTransactions (be, grp);
@@ -662,7 +665,9 @@ pgendSyncPriceDB (Backend *bend, GNCPriceDB *prdb)
 {
    PGBackend *be = (PGBackend *)bend;
    ENTER ("be=%p, prdb=%p", be, prdb);
+   if (!be || !prdb) return;
 
+   be->version_check = (guint32) time(0);
    pgendStorePriceDB (be, prdb);
 
    /* don't send events  to GUI, don't accept callbacks to backend */
@@ -1033,6 +1038,7 @@ pgend_book_load_poll (Backend *bend)
    /* don't send events  to GUI, don't accept callbacks to backend */
    gnc_engine_suspend_events();
    pgendDisable(be);
+   be->version_check = (guint32) time(0);
 
    pgendKVPInit(be);
    grp = pgendGetAllAccounts (be, NULL);
@@ -1088,6 +1094,7 @@ pgend_book_load_single (Backend *bend)
    /* don't send events  to GUI, don't accept callbacks to backend */
    gnc_engine_suspend_events();
    pgendDisable(be);
+   be->version_check = (guint32) time(0);
 
    pgendKVPInit(be);
    grp = pgendGetAllAccounts (be, NULL);
@@ -1116,6 +1123,7 @@ pgend_price_load_single (Backend *bend)
    /* don't send events  to GUI, don't accept callbacks to backend */
    gnc_engine_suspend_events();
    pgendDisable(be);
+   be->version_check = (guint32) time(0);
 
    prdb = pgendGetAllPrices (be, NULL);
 
@@ -1751,6 +1759,8 @@ pgendInit (PGBackend *be)
    be->last_price = ts;
    be->last_transaction = ts;
 
+   be->version_check = (guint32) ts.tv_sec;
+
    be->builder = sqlBuilder_new();
 
    be->buff = g_malloc (QBUFSIZE);

src/engine/sql/PostgresBackend.h

@@ -53,6 +53,8 @@ typedef enum {
    MODE_EVENT
 } AccessMode;
 
+#define MAX_VERSION_AGE 10
+
 struct _pgend {
    Backend be;
 
@@ -91,6 +93,8 @@ struct _pgend {
    Timespec last_price;
    Timespec last_transaction;
 
+   guint32 version_check; /* data aging timestamp */
+
    /* scratch space for constructing queries */ 
    int bufflen;
    char *buff;

src/engine/sql/README

@@ -336,8 +336,8 @@ operation is probably OK.
    backend can't contact its server, then we should just save up caches,
    and then when contact with backend re-established, we should spit
    them out.  The pgendSync routine should more or less do the trick;
-   note, however, that the file format needs to save the version number
-   ...
+   note, however, that the XML file format needs to save the version 
+   number ...
 
 -- Implement various advanced database features, such as checking the
    user's permission to view/edit account by account ... (hmmm this

src/engine/sql/account.c

@@ -107,6 +107,7 @@ pgendStoreAccountNoLock (PGBackend *be, Account *acct,
      if (0 < pgendAccountCompareVersion (be, acct)) return;
    }
    acct->version ++;  /* be sure to update the version !! */
+   acct->version_check = be->version_check;
 
    pgendPutOneAccountOnly (be, acct);
 
@@ -395,7 +396,16 @@ pgendCopyAccountToEngine (PGBackend *be, const GUID *acct_guid)
    } 
    else
    {
-      engine_data_is_newer = - pgendAccountCompareVersion (be, acc);
+      /* save some performance, don't go to the backend if the data is recent. */
+      if (MAX_VERSION_AGE >= be->version_check - acc->version_check) 
+      {
+         PINFO ("fresh data, skip check");
+         engine_data_is_newer = 0;
+      }
+      else 
+      {
+         engine_data_is_newer = - pgendAccountCompareVersion (be, acc);
+      }
    }
 
    if (0 > engine_data_is_newer)
@@ -416,6 +426,8 @@ pgendCopyAccountToEngine (PGBackend *be, const GUID *acct_guid)
       acc->kvp_data = pgendKVPFetch (be, &(acc->guid), acc->kvp_data);
 
       pgendGetAccountCurrencyHack (be, acc);
+
+      acc->version_check = be->version_check;
    }
 
    /* re-enable events to the backend and GUI */
@@ -478,6 +490,7 @@ pgend_account_commit_edit (Backend * bend,
       return 445;
    }
    acct->version ++;   /* be sure to update the version !! */
+   acct->version_check = be->version_check;
 
    if (acct->do_free)
    {

src/engine/sql/design.txt

@@ -214,8 +214,6 @@ are not using NTP for time synchronization; or, e.g. if one machine failed
 to have daylight-savings time set correctly: its transactions would be 
 an hour newer/older than the others, leading to bad updates).
 
-Prices need to have version numbers added.
-
 /* The pgendAccountCompareVersion() routine compares the version
  * number of the account in the engine and the sql database. It
  * returns a negative number if the sql version is older (or the
@@ -224,6 +222,23 @@ Prices need to have version numbers added.
  * two are equal.
  */
 
+Version numbers need to be written to XML file
+
+Version Timestamp
+-----------------
+The engine is structured so that whenever the GUI issues a query, that 
+query is passed to the backend. (The engine assumes the worst: that
+the engine data cache is out of date and needs to be upgraded.)  
+Unforunately, the GUI frequently queries for the same data several 
+times in rapid succession.  If this is taken at face value, then 
+multiple redundant queries to the SQL server occur in quick succession.
+
+The version_check field is used to minimize these redundant queries.
+It stores a timestamp; if the timestamp is less than 10 seconds old
+(MAX_VERSION_AGE), then the backend assumes that the engine data is
+sufficiently recent, and the sql query is skipped.  Under certain 
+situations, a considerable amount of querying can be avoided.
+
 
 Audit Trails
 ------------

src/engine/sql/price.c

@@ -117,6 +117,7 @@ pgendStorePriceNoLock (PGBackend *be, GNCPrice *pr,
      if (0 < pgendPriceCompareVersion (be, pr)) return;
    }
    pr->version ++;  /* be sure to update the version !! */
+   pr->version_check = be->version_check;
 
    /* make sure that we've stored the commodity 
     * and currency before we store the price.
@@ -442,6 +443,7 @@ pgend_price_commit_edit (Backend * bend, GNCPrice *pr)
       return 445;
    }
    pr->version ++;   /* be sure to update the version !! */
+   pr->version_check = be->version_check;
 
    if (pr->do_free) 
    {

src/engine/sql/txn.c

@@ -129,6 +129,7 @@ pgendStoreTransactionNoLock (PGBackend *be, Transaction *trans,
       if (0 < pgendTransactionCompareVersion (be, trans)) return;
    }
    trans->version ++;  /* be sure to update the version !! */
+   trans->version_check = be->version_check;
 
    /* first, we need to see which splits are in the database
     * since what is there may not match what we have cached in 
@@ -368,6 +369,17 @@ pgendCopyTransactionToEngine (PGBackend *be, const GUID *trans_guid)
       do_set_guid=TRUE;
       engine_data_is_newer = -1;
    }
+   else 
+   {
+      /* save some performance, don't go to the backend if the data is recent. */
+      if (MAX_VERSION_AGE >= be->version_check - trans->version_check) 
+      {
+         PINFO ("fresh data, skip check");
+         pgendEnable(be);
+         gnc_engine_resume_events();
+         return 0;
+      }
+   }
 
    /* build the sql query to get the transaction */
    pbuff = be->buff;
@@ -470,6 +482,9 @@ pgendCopyTransactionToEngine (PGBackend *be, const GUID *trans_guid)
       i++;
    } while (result);
 
+   /* set timestamp as 'recent' for this data */
+   trans->version_check = be->version_check;
+
    /* if engine data was newer, we are done */
    if (0 <= engine_data_is_newer) 
    {