Additional debugging and tracing logic for pcache.c, turned off by default

using an "#if 0".

FossilOrigin-Name: 32a62e3bd46cf58586617d3f8b1a971c91df205e

manifest

@@ -1,5 +1,5 @@
-C Disable\sALWAYS\sand\sNEVER\swhen\scompiled\swith\sSQLITE_MUTATION_TEST.
+C Additional\sdebugging\sand\stracing\slogic\sfor\spcache.c,\sturned\soff\sby\sdefault\nusing\san\s"#if\s0".
-D 2016-05-12T19:17:09.294
+D 2016-05-13T04:24:25.046
 F Makefile.in 9eda6e1c90d05c199c3ec8a7069b0682ad307657
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc db82b35aef27f412fef14d8534afc022138bcdfd
@@ -367,7 +367,7 @@ F src/os_win.h eb7a47aa17b26b77eb97e4823f20a00b8bda12ca
 F src/pager.c b6b3f2aff301cb025b23a8586666c91355cb3c69
 F src/pager.h 329bdf078a4e0a3b35084534d58625d21fd03681
 F src/parse.y 10eb2f3fb62341291528c7984498054731f9d31e
-F src/pcache.c 3ef140add88d8d3eee3a80a79412f450bd216d3b
+F src/pcache.c ad5ce697dc5a734caddb2b1eac83b195da95ddbe
 F src/pcache.h 33b40350df1b6c278e019dee37f87e1bac276223
 F src/pcache1.c 7f51d2b541aab57596adf62db2c4bb025d34f04d
 F src/pragma.c faf42922bb7ab2f6672cb550356c1967abae3c84
@@ -1488,7 +1488,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 1b0f4cc362cda1dc175aa363ae4e612b7d1164c3
+P 24d9fbc1d0f99b90577ecd6edcd3bc1abc76633f
-R cbaa515ed65f02858509b96594eef6a3
+R d638f11a5a2154aefeed14f79e8ebc4d
 U drh
-Z d111db0e0c72ae873465e360a322abe1
+Z 291bccc6a32f88cd8cda8747cf2307e8

manifest.uuid

@@ -1 +1 @@
-24d9fbc1d0f99b90577ecd6edcd3bc1abc76633f
+32a62e3bd46cf58586617d3f8b1a971c91df205e

src/pcache.c

@@ -57,10 +57,35 @@ struct PCache {
 ** Debug tracing macros
 */
 #if defined(SQLITE_DEBUG) && 0
-  int sqlite3PcacheTrace = 1;
+  int sqlite3PcacheTrace = 2;
 # define pcacheTrace(X) if(sqlite3PcacheTrace){sqlite3DebugPrintf X;}
-#else
+  void pcacheDump(PCache *pCache){
+    int N;
+    int i, j;
+    sqlite3_pcache_page *pLower;
+    PgHdr *pPg;
+    unsigned char *a;
+  
+    if( sqlite3PcacheTrace<2 ) return;
+    if( pCache->pCache==0 ) return;
+    N = sqlite3PcachePagecount(pCache);
+    if( N>5 ) N = 5;
+    for(i=1; i<=N; i++){
+       pLower = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, i, 0);
+       if( pLower==0 ) continue;
+       pPg = (PgHdr*)pLower->pExtra;
+       printf("%3d: nRef %2d flgs %02x data ", i, pPg->nRef, pPg->flags);
+       a = (unsigned char *)pLower->pBuf;
+       for(j=0; j<12; j++) printf("%02x", a[j]);
+       printf("\n");
+       if( pPg->pPage==0 ){
+         sqlite3GlobalConfig.pcache2.xUnpin(pCache->pCache, pLower, 0);
+       }
+    }
+  }
+  #else
 # define pcacheTrace(X)
+# define pcacheDump(X)
 #endif
 
 /********************************** Linked List Management ********************/
@@ -142,6 +167,7 @@ static void pcacheManageDirtyList(PgHdr *pPage, u8 addRemove){
       p->pSynced = pPage;
     }
   }
+  pcacheDump(p);
 }
 
 /*
@@ -152,6 +178,7 @@ static void pcacheUnpin(PgHdr *p){
   if( p->pCache->bPurgeable ){
     pcacheTrace(("%p.UNPIN %d\n", p->pCache, p->pgno));
     sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 0);
+    pcacheDump(p->pCache);
   }
 }
 
@@ -352,6 +379,7 @@ int sqlite3PcacheFetchStress(
 #endif
       pcacheTrace(("%p.SPILL %d\n",pCache,pPg->pgno));
       rc = pCache->xStress(pCache->pStress, pPg);
+      pcacheDump(pCache);
       if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
         return rc;
       }
@@ -496,6 +524,7 @@ void sqlite3PcacheMakeClean(PgHdr *p){
 */
 void sqlite3PcacheCleanAll(PCache *pCache){
   PgHdr *p;
+  pcacheTrace(("%p.CLEAN-ALL\n",pCache));
   while( (p = pCache->pDirty)!=0 ){
     sqlite3PcacheMakeClean(p);
   }
@@ -506,6 +535,7 @@ void sqlite3PcacheCleanAll(PCache *pCache){
 */
 void sqlite3PcacheClearWritable(PCache *pCache){
   PgHdr *p;
+  pcacheTrace(("%p.CLEAR-WRITEABLE\n",pCache));
   for(p=pCache->pDirty; p; p=p->pDirtyNext){
     p->flags &= ~(PGHDR_NEED_SYNC|PGHDR_WRITEABLE);
   }