From: drh <drh@noemail.net>
Date: Tue, 20 Feb 2018 15:23:37 +0000 (+0000)
Subject: Optimize calls to sqlite3_mprintf("%z...") so that they attempt to append
X-Git-Tag: version-3.23.0~115
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=cc398969e058b006bf87e35700b366977fc8682c;p=thirdparty%2Fsqlite.git

Optimize calls to sqlite3_mprintf("%z...") so that they attempt to append
text onto the end of the existing memory allocation rather than reallocating
and copying.

FossilOrigin-Name: 4bc8a48e644562f6e6192f4c6fc4a70f6bb59f8126ed6c6dc876bedf65d74cda
---

diff --git a/Makefile.in b/Makefile.in
index 7bc413e843..1766ca580e 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -591,6 +591,7 @@ SHELL_OPT += -DSQLITE_INTROSPECTION_PRAGMAS
 FUZZERSHELL_OPT = -DSQLITE_ENABLE_JSON1
 FUZZCHECK_OPT = -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_MEMSYS5 -DSQLITE_OSS_FUZZ
 FUZZCHECK_OPT += -DSQLITE_MAX_MEMORY=50000000
+FUZZCHECK_OPT += -DSQLITE_PRINTF_PRECISION_LIMIT=1000
 FUZZCHECK_SRC = $(TOP)/test/fuzzcheck.c $(TOP)/test/ossfuzz.c
 DBFUZZ_OPT = 
 
diff --git a/Makefile.msc b/Makefile.msc
index 875aeedeab..af053cd615 100644
--- a/Makefile.msc
+++ b/Makefile.msc
@@ -1615,7 +1615,7 @@ SHELL_COMPILE_OPTS = $(SHELL_COMPILE_OPTS) -DSQLITE_ENABLE_RTREE
 #
 MPTESTER_COMPILE_OPTS = -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_FTS5
 FUZZERSHELL_COMPILE_OPTS = -DSQLITE_ENABLE_JSON1
-FUZZCHECK_COMPILE_OPTS = -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_MEMSYS5 -DSQLITE_OSS_FUZZ -DSQLITE_MAX_MEMORY=50000000
+FUZZCHECK_COMPILE_OPTS = -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_MEMSYS5 -DSQLITE_OSS_FUZZ -DSQLITE_MAX_MEMORY=50000000 -DSQLITE_PRINTF_PRECISION_LIMIT=1000
 FUZZCHECK_SRC = $(TOP)\test\fuzzcheck.c $(TOP)\test\ossfuzz.c
 OSSSHELL_SRC = $(TOP)\test\ossshell.c $(TOP)\test\ossfuzz.c
 DBFUZZ_COMPILE_OPTS = -DSQLITE_THREADSAFE=0 -DSQLITE_OMIT_LOAD_EXTENSION
diff --git a/main.mk b/main.mk
index 2eddfc6f27..c5a0aa6cd3 100644
--- a/main.mk
+++ b/main.mk
@@ -519,6 +519,7 @@ SHELL_OPT += -DSQLITE_INTROSPECTION_PRAGMAS
 FUZZERSHELL_OPT = -DSQLITE_ENABLE_JSON1
 FUZZCHECK_OPT = -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_MEMSYS5
 FUZZCHECK_OPT += -DSQLITE_MAX_MEMORY=50000000
+FUZZCHECK_OPT += -DSQLITE_PRINTF_PRECISION_LIMIT=1000
 DBFUZZ_OPT =
 KV_OPT = -DSQLITE_THREADSAFE=0 -DSQLITE_DIRECT_OVERFLOW_READ
 ST_OPT = -DSQLITE_THREADSAFE=0
diff --git a/manifest b/manifest
index 9788e54316..76a5ca6866 100644
--- a/manifest
+++ b/manifest
@@ -1,10 +1,10 @@
-C Remove\sa\slot\sof\sthe\stext\sdescribing\sextended\sformat\soptions\sfrom\sthe\ndocumentation\son\ssqlite3_mprintf()\sand\sfriends,\ssince\sthat\sinformation\sis\nnow\scovered\sby\sthe\sseparate\sprintf.html\sdocument.\s\sProvide\slinks\sto\sthat\nother\sdocument.\s\sNo\schanges\sto\scode.
-D 2018-02-20T13:46:20.902
+C Optimize\scalls\sto\ssqlite3_mprintf("%z...")\sso\sthat\sthey\sattempt\sto\sappend\ntext\sonto\sthe\send\sof\sthe\sexisting\smemory\sallocation\srather\sthan\sreallocating\nand\scopying.
+D 2018-02-20T15:23:37.534
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
-F Makefile.in 7a3f714b4fcf793108042b7b0a5c720b0b310ec84314d61ba7f3f49f27e550ea
+F Makefile.in a2d2fb8d17c39ab5ec52beb27850b903949080848236923f436156b72a958737
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
-F Makefile.msc b5e9eb7212c5a61d4800172c710376d1158fd5eea2edc0be8e05c0c372e767e4
+F Makefile.msc b53ebf2538324c914e4308a6cd44610eb1ae50bdbd17d7ee65f680918e54da88
 F README.md d748f58e3ab0fe0307fb4ae0942b415d93dcc4288756e366cc9e7cf8260c093f
 F VERSION cdf91ac446255ecf3d8f6d8c3ee40d64123235ae5b3cef29d344e61b45ec3759
 F aclocal.m4 a5c22d164aff7ed549d53a90fa56d56955281f50
@@ -411,7 +411,7 @@ F ext/userauth/userauth.c 3410be31283abba70255d71fd24734e017a4497f
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
 F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
 F magic.txt 8273bf49ba3b0c8559cb2774495390c31fd61c60
-F main.mk c8c473bd91d553acab3fb0608ddb69fc769c7bcf6d9e258800504bfda86c792b
+F main.mk 04969462bfd32c9f08d4a6d40622e8c43c8c5ecfb2ee52ffb5737c5eca4b0c03
 F mkso.sh fd21c06b063bb16a5d25deea1752c2da6ac3ed83
 F mptest/config01.test 3c6adcbc50b991866855f1977ff172eb6d901271
 F mptest/config02.test 4415dfe36c48785f751e16e32c20b077c28ae504
@@ -484,7 +484,7 @@ F src/pcache1.c 716975564c15eb6679e97f734cec1bfd6c16ac3d4010f05f1f8e509fc7d19880
 F src/pragma.c bea56df3ae0637768c0da4fbbb8f2492f780980d95000034a105ff291bf7ca69
 F src/pragma.h bb83728944b42f6d409c77f5838a8edbdb0fe83046c5496ffc9602b40340a324
 F src/prepare.c 259f4e7960c47082c9653f3d5f0c294abd68bb9c3aab86de7630700cba1c20fb
-F src/printf.c 07244a9e1755247c9543db551acd2f3cce461b28d13e9f3ab87053c35fd62717
+F src/printf.c d3b7844ddeb11fbbdd38dd84d09c9c1ac171d21fb038473c3aa97981201cc660
 F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
 F src/resolve.c bbee7e31d369a18a2f4836644769882e9c5d40ef4a3af911db06410b65cb3730
 F src/rowset.c 7b7e7e479212e65b723bf40128c7b36dc5afdfac
@@ -1707,7 +1707,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P c883c4d33f4cd722982aca17eeb355d19eeed793991d923b5494d173b1d0c73a
-R 2031e9cc56213989aa9a3f7b2af81256
+P 99eec556f065ad19548e48d1f4ae0a3767b4e82e1c83fa2365062e3c5e0071fb
+R 7c8988fb832914bacef8f6a6a302789a
 U drh
-Z 242cc6a18e31e977a6ec01c768dc69ec
+Z 0178b35e80c45b1a39d6c8cc991625e8
diff --git a/manifest.uuid b/manifest.uuid
index 736ace92ca..9279bc5dbb 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-99eec556f065ad19548e48d1f4ae0a3767b4e82e1c83fa2365062e3c5e0071fb
\ No newline at end of file
+4bc8a48e644562f6e6192f4c6fc4a70f6bb59f8126ed6c6dc876bedf65d74cda
\ No newline at end of file
diff --git a/src/printf.c b/src/printf.c
index 11d5b82828..fcbd7fdbe0 100644
--- a/src/printf.c
+++ b/src/printf.c
@@ -206,6 +206,11 @@ void sqlite3VXPrintf(
   PrintfArguments *pArgList = 0; /* Arguments for SQLITE_PRINTF_SQLFUNC */
   char buf[etBUFSIZE];       /* Conversion buffer */
 
+  /* pAccum never starts out with an empty buffer that was obtained from 
+  ** malloc().  This precondition is required by the mprintf("%z...")
+  ** optimization. */
+  assert( pAccum->nChar>0 || (pAccum->printfFlags&SQLITE_PRINTF_MALLOCED)==0 );
+
   bufpt = 0;
   if( (pAccum->printfFlags & SQLITE_PRINTF_SQLFUNC)!=0 ){
     pArgList = va_arg(ap, PrintfArguments*);
@@ -681,6 +686,18 @@ void sqlite3VXPrintf(
         if( bufpt==0 ){
           bufpt = "";
         }else if( xtype==etDYNSTRING ){
+          if( pAccum->nChar==0 && pAccum->mxAlloc && width==0 && precision<0 ){
+            /* Special optimization for sqlite3_mprintf("%z..."):
+            ** Extend an existing memory allocation rather than creating
+            ** a new one. */
+            assert( (pAccum->printfFlags&SQLITE_PRINTF_MALLOCED)==0 );
+            pAccum->zText = bufpt;
+            pAccum->nAlloc = sqlite3DbMallocSize(pAccum->db, bufpt);
+            pAccum->nChar = 0x7fffffff & (int)strlen(bufpt);
+            pAccum->printfFlags |= SQLITE_PRINTF_MALLOCED;
+            length = 0;
+            break;
+          }
           zExtra = bufpt;
         }
         if( precision>=0 ){