The sqlite3_snapshot_describe() interface useful for debugging snapshot logic.

FossilOrigin-Name: 3fbfa9a8e88e354d113e7b30c948dbf8bf6d53d93b2fc69652a3ff58dbf4df57

diff --git a/manifest b/manifest
index 3992ec18ab1d5c45aa2f751719a195322781d83f..3dc11249b6cabcd7a9240c30b21ec75ef2791871 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Revert\sone\sperformance\simprovement\schanges\sfrom\scheck-in\s[3b3e32d4cd07]\sas\nit\swas\scausing\sa\sreference\sto\san\suninitialized\svalue.
-D 2017-09-21T01:04:30.271
+C The\ssqlite3_snapshot_describe()\sinterface\suseful\sfor\sdebugging\ssnapshot\slogic.
+D 2017-09-21T14:03:59.304
 F Makefile.in 4bc36d913c2e3e2d326d588d72f618ac9788b2fd4b7efda61102611a6495c3ff
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 6033b51b6aea702ea059f6ab2d47b1d3cef648695f787247dd4fb395fe60673f
@@ -461,7 +461,7 @@ F src/rowset.c 7b7e7e479212e65b723bf40128c7b36dc5afdfac
 F src/select.c 9fa0db382f43217e207a145b8c6cec26e85cd1a42a8428ee8b3df5870dfea0f4
 F src/shell.c c1206a23d9239f8f51751d3be9b8c3b02fa4103546bea1add7f864d84a8276ab
 F src/shell.c.in bb9720a8c5c98d3984b16ab7540e7142bcae959666ecf248bfc523a1d44220ee
-F src/sqlite.h.in ab4f8a29d1580dfaeb6891fa1b83cff8229ba0daa56994707ceaca71495d9ab7
+F src/sqlite.h.in 41d873beefa82473dbbcffc9af29a87d7ce9be918a58d97312f1ce2bc3062abb
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h a1fd3aa82f967da436164e0728a7d6841651fd0c6e27b9044e0eb9f6c8462e47
 F src/sqliteInt.h 12aa1f626b3209ffa6a50d9d1e6b4235abd33273a0fcbfeedb66f573a68932b9
@@ -537,7 +537,7 @@ F src/vdbesort.c 731a09e5cb9e96b70c394c1b7cf3860fbe84acca7682e178615eb941a3a0ef2
 F src/vdbetrace.c 48e11ebe040c6b41d146abed2602e3d00d621d7ebe4eb29b0a0f1617fd3c2f6c
 F src/vtab.c f1d5c23132fb0247af3e86146404112283ddedb6c518de0d4edc91cfb36970ef
 F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
-F src/wal.c 839db09792fead5052bb35e533fa485e134913d547d05b5f42e537b73e63f07a
+F src/wal.c 0f3fc4059289142998100d38f98e4b89ee23a9fb450438d4c27b7c1721bd6452
 F src/wal.h 8de5d2d3de0956d6f6cb48c83a4012d5f227b8fe940f3a349a4b7e85ebcb492a
 F src/walker.c 3ccfa8637f95355bff61144e01a615b8ef26f79c312880848da73f03367da1e6
 F src/where.c 21eea981920a13fd3c0ac3d6c128d0a34b22cbec064e4f0603375fe1ffe26ca6
@@ -1655,7 +1655,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P adc12c83dda8ba93ca220bbff649f763058b9440968ae463621f0cb7de8889cf
-R 74e9a42e62567d447ce10652f9c93fed
+P f8b1c64d3eeb8413ca149f34cc00f9154a5446d06ad33bbffa69118e6110f81d
+R 5b5eb921c8efc28de7d196a6a9e85cac
+T *branch * sqlite3_snapshot_describe
+T *sym-sqlite3_snapshot_describe *
+T -sym-trunk *
 U drh
-Z 07fc711a459108ff2c2431795ab36ea3
+Z 6a46e389b1ff02d5f104988f972409a5

diff --git a/manifest.uuid b/manifest.uuid
index 4aaeed6a9dee222fe85f8ea124b207416c39fd2a..ba3f44d8be16b9ea6fb195b8d3d2a5a8d15a9970 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-f8b1c64d3eeb8413ca149f34cc00f9154a5446d06ad33bbffa69118e6110f81d
\ No newline at end of file
+3fbfa9a8e88e354d113e7b30c948dbf8bf6d53d93b2fc69652a3ff58dbf4df57
\ No newline at end of file

diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index 9ff366304f201a3198c817924a6a10f4d695ee93..1c9aa0e9401d6eb62be17f9ae6b3b63807258079 100644 (file)
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -8575,6 +8575,7 @@ typedef struct sqlite3_snapshot {
 
 /*
 ** CAPI3REF: Record A Database Snapshot
+** CONSTRUCTOR: sqlite3_snapshot
 ** EXPERIMENTAL
 **
 ** ^The [sqlite3_snapshot_get(D,S,P)] interface attempts to make a
@@ -8662,6 +8663,7 @@ SQLITE_EXPERIMENTAL int sqlite3_snapshot_open(
 
 /*
 ** CAPI3REF: Destroy a snapshot
+** DESTRUCTOR: sqlite3_snapshot
 ** EXPERIMENTAL
 **
 ** ^The [sqlite3_snapshot_free(P)] interface destroys [sqlite3_snapshot] P.
@@ -8722,6 +8724,30 @@ SQLITE_EXPERIMENTAL int sqlite3_snapshot_cmp(
 */
 SQLITE_EXPERIMENTAL int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb);
 
+
+/*
+** CAPI3REF: Human-readable description of a snapshot
+** EXPERIMENTAL
+**
+** The sqlite3_snapshot_describe(S,B,N) interface writes a human-readable
+** description of snapshot S into the array of characters B of length N.
+** As long as N is greater than 0, the string written into B is guaranteed
+** to be zero terminated.
+**
+** This routine is intended for testing and debugging use only. The details
+** of the text description written into B may vary from one release to the
+** next.
+**
+** The [sqlite3_snapshot_describe()] interface is only available when the
+** both the [SQLITE_ENABLE_SNAPSHOT] an [SQLITE_DEBUG] compile-time options
+** are used.
+*/
+SQLITE_EXPERIMENTAL void sqlite3_snapshot_describe(
+  sqlite3_snapshot*,   /* The snapshot to be described */
+  char *pBuf,          /* Write the description into this buffer */
+  int nBuf             /* Length of pBuf in bytes */
+);
+
 /*
 ** Undo the hack that converts floating point types to integer for
 ** builds on processors without floating point support.

diff --git a/src/wal.c b/src/wal.c
index 9930b84421bceaf572619617215fa5d767359647..f49ee655fab8a8dff59e6aafbfd3bf1f5696d887 100644 (file)
--- a/src/wal.c
+++ b/src/wal.c
@@ -3514,6 +3514,29 @@ int sqlite3_snapshot_cmp(sqlite3_snapshot *p1, sqlite3_snapshot *p2){
   if( pHdr1->mxFrame>pHdr2->mxFrame ) return +1;
   return 0;
 }
+
+/*
+** Write a human-readable description of a snapshot into a text buffer.
+*/
+void sqlite3_snapshot_describe(sqlite3_snapshot *pSS, char *z, int n){
+  WalIndexHdr *p = (WalIndexHdr*)pSS;
+  sqlite3_snprintf(n,z,
+     "mxFrame %u "
+     "nPage %u "
+     "szPage %u "
+     "iChange %u "
+     "aFrameCksum 0x%08x%08x "
+     "aSalt 0x%08x%08x "
+     "iVersion %u ",
+     p->mxFrame,
+     p->nPage,
+     p->szPage,
+     p->iChange,
+     p->aFrameCksum[0], p->aFrameCksum[1],
+     p->aSalt[0], p->aSalt[1],
+     p->iVersion
+  );
+}
 #endif /* SQLITE_ENABLE_SNAPSHOT */
 
 #ifdef SQLITE_ENABLE_ZIPVFS