Add some docs and metrics for the new mutex internals.

FossilOrigin-Name: 33d1780b43182d2574adbc1928707af825c485c99762738e58bc6d7c6c52ac6a

diff --git a/ext/jni/src/c/sqlite3-jni.c b/ext/jni/src/c/sqlite3-jni.c
index 4522e05b45705756ea01275d15c7607f2bd56f30..eebe124f8941d6b2cc78aa355e59c71da2257ce9 100644 (file)
--- a/ext/jni/src/c/sqlite3-jni.c
+++ b/ext/jni/src/c/sqlite3-jni.c
@@ -499,19 +499,25 @@ static struct {
     S3JniEnvCache * aHead /* Linked list of in-use instances */;
     S3JniEnvCache * aFree /* Linked list of free instances */;
     sqlite3_mutex * mutex /* mutex for aHead and aFree */;
-    void const * locker   /* env mutex is held on this object's behalf */;
+    void const * locker   /* env mutex is held on this object's behalf
+                             (used only for sanity checking). */;
   } envCache;
   struct {
     S3JniDb * aUsed  /* Linked list of in-use instances */;
     S3JniDb * aFree  /* Linked list of free instances */;
-    sqlite3_mutex * mutex  /* mutex for aUsed and aFree */;
-    void const * locker   /* perDb mutex is held on this object's behalf */;
+    sqlite3_mutex * mutex /* mutex for aUsed and aFree */;
+    void const * locker   /* perDb mutex is held on this object's
+                             behalf.  Unlike envCache.locker, we
+                             cannot always have this set to the
+                             current JNIEnv object. */;
   } perDb;
   struct {
     unsigned nphCacheHits;
     unsigned nphCacheMisses;
     unsigned envCacheHits;
     unsigned envCacheMisses;
+    unsigned nMutexEnv       /* number of times envCache.mutex was entered */;
+    unsigned nMutexPerDb     /* number of times perDb.mutex was entered */;
     unsigned nDestroy        /* xDestroy() calls across all types */;
     struct {
       /* Number of calls for each type of UDF callback. */
@@ -542,30 +548,28 @@ static struct {
 
 #define MUTEX_ASSERT_LOCKER_ENV                                      \
   assert( (env) == S3JniGlobal.envCache.locker && "Misuse of S3JniGlobal.envCache.mutex" )
-#define MUTEX_ASSERT_LOCKER_PDB                                      \
-  assert( 0 != S3JniGlobal.perDb.locker && "Misuse of S3JniGlobal.perDb.mutex" )
 #define MUTEX_ASSERT_NOTLOCKER_ENV                                   \
   assert( (env) != S3JniGlobal.envCache.locker && "Misuse of S3JniGlobal.envCache.mutex" )
-#define MUTEX_ASSERT_NOTLOCKER_PDB                                   \
-  assert( 0 == S3JniGlobal.perDb.locker && "Misuse of S3JniGlobal.perDb.mutex" )
 #define MUTEX_ENTER_ENV                          \
   /*MARKER(("Entering ENV mutex@%p %s.\n", env, __func__));*/ \
   MUTEX_ASSERT_NOTLOCKER_ENV;                      \
   sqlite3_mutex_enter( S3JniGlobal.envCache.mutex ); \
+  ++S3JniGlobal.metrics.nMutexEnv;                \
   S3JniGlobal.envCache.locker = env
 #define MUTEX_LEAVE_ENV                          \
   /*MARKER(("Leaving ENV mutex @%p %s.\n", env, __func__));*/ \
   MUTEX_ASSERT_LOCKER_ENV;                       \
   S3JniGlobal.envCache.locker = 0;                \
   sqlite3_mutex_leave( S3JniGlobal.envCache.mutex )
+#define MUTEX_ASSERT_LOCKED_PDB                                      \
+  assert( 0 != S3JniGlobal.perDb.locker && "Misuse of S3JniGlobal.perDb.mutex" )
 #define MUTEX_ENTER_PDB                            \
   /*MARKER(("Entering PerDb mutex@%p %s.\n", env, __func__));*/ \
-  MUTEX_ASSERT_NOTLOCKER_PDB;                      \
   sqlite3_mutex_enter( S3JniGlobal.perDb.mutex );  \
+  ++S3JniGlobal.metrics.nMutexPerDb;               \
   S3JniGlobal.perDb.locker = env;
 #define MUTEX_LEAVE_PDB         \
   /*MARKER(("Leaving PerDb mutex@%p %s.\n", env, __func__));*/  \
-  MUTEX_ASSERT_LOCKER_PDB;      \
   S3JniGlobal.perDb.locker = 0; \
   sqlite3_mutex_leave( S3JniGlobal.perDb.mutex )
 
@@ -899,7 +903,7 @@ static void S3JniHook_unref(JNIEnv * const env, S3JniHook * const s, int doXDest
 static void S3JniDb_set_aside(S3JniDb * const s){
   if(s){
     JNIEnv * const env = s->env;
-    MUTEX_ASSERT_LOCKER_PDB;
+    MUTEX_ASSERT_LOCKED_PDB;
     assert(s->pDb && "Else this object is already in the free-list.");
     //MARKER(("state@%p for db@%p setting aside\n", s, s->pDb));
     assert(s->pPrev != s);
@@ -1035,6 +1039,10 @@ static S3JniNphCache * S3JniGlobal_nph_cache(JNIEnv * const env, const char *zCl
      you should look them up once and then reuse them. Similarly,
      looking up class objects can be expensive, so they should be
      cached as well.
+
+     Reminder: we do not need a mutex for the envRow->nph cache
+     because all nph entries are per-thread and envCache.mutex
+     already guards the fetching of envRow.
   */
   struct S3JniEnvCache * const envRow = S3JniGlobal_env_cache(env);
   S3JniNphCache * freeSlot = 0;
@@ -1153,7 +1161,7 @@ static void * NativePointerHolder_get(JNIEnv * env, jobject pObj, const char *zC
 static S3JniDb * S3JniDb_alloc(JNIEnv * const env, sqlite3 *pDb,
                                jobject jDb){
   S3JniDb * rv;
-  MUTEX_ASSERT_LOCKER_PDB;
+  MUTEX_ASSERT_LOCKED_PDB;
   if(S3JniGlobal.perDb.aFree){
     rv = S3JniGlobal.perDb.aFree;
     //MARKER(("state@%p for db allocating for db@%p from free-list\n", rv, pDb));
@@ -3496,6 +3504,9 @@ JDECL(void,1do_1something_1for_1developer)(JENV_CSELF){
   printf("\tJNIEnv cache               %u misses, %u hits\n",
          S3JniGlobal.metrics.envCacheMisses,
          S3JniGlobal.metrics.envCacheHits);
+  printf("\tMutex entry: %u env, %u perDb\n",
+         S3JniGlobal.metrics.nMutexEnv,
+         S3JniGlobal.metrics.nMutexPerDb);
   puts("Java-side UDF calls:");
 #define UDF(T) printf("\t%-8s = %u\n", "x" #T, S3JniGlobal.metrics.udf.n##T)
   UDF(Func); UDF(Step); UDF(Final); UDF(Value); UDF(Inverse);

diff --git a/manifest b/manifest
index d3b949dbf94d6fd03da07aafbd0640eb323f88bd..48db0129dae17c23a164a61c40ed728431f193d9 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C An\sinitial\sattempt\sat\sprotecting\sthe\sJNI\sglobal\sstate\svia\smutexes\sat\sthe\sC\slevel\sinstead\sof\srelying\son\sJava's\ssynchronized\skeyword.\sIt\sseems\sto\swork\sbut\sincreases\sthe\srun\stime\sof\sthe\ssingle-threaded\sbatch\stester\sby\sroughly\s3\stimes.
-D 2023-08-13T09:53:27.824
+C Add\ssome\sdocs\sand\smetrics\sfor\sthe\snew\smutex\sinternals.
+D 2023-08-13T10:28:35.456
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -234,7 +234,7 @@ F ext/icu/sqliteicu.h fa373836ed5a1ee7478bdf8a1650689294e41d0c89c1daab26e9ae78a3
 F ext/jni/GNUmakefile a9e11b92e620058558cbc1a2d49f8ec53c78d6a989b9db0b7d0b649b9f174881
 F ext/jni/README.md 7a614a2fa6c561205f7a53fd8626cf93a7b5711ff454fc1814517f796df398eb
 F ext/jni/jar-dist.make f90a553203a57934bf275bed86479485135a52f48ac5c1cfe6499ae07b0b35a4
-F ext/jni/src/c/sqlite3-jni.c 93fbeed06441352df68f6c0e4bc2cd895e81d8550dc9972cafb30621958b4784
+F ext/jni/src/c/sqlite3-jni.c 44c1da6d1ae9d8ea2af16dd5c1d17224a655c9c94135892f81571b2481896431
 F ext/jni/src/c/sqlite3-jni.h f10d2f38720687c70ecdd5e44f6e8db98efee2caa05fc86b2d9e0c76e6cc0a18
 F ext/jni/src/org/sqlite/jni/Authorizer.java 1308988f7f40579ea0e4deeaec3c6be971630566bd021c31367fe3f5140db892
 F ext/jni/src/org/sqlite/jni/AutoExtension.java 18e83f6f463e306df60b2dceb65247d32af1f78af4bbbae9155411a8c6cdb093
@@ -2091,8 +2091,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P fbf99a2423dd20e4544bdeea85f714e9368ce3b92fefe97efb39a0fb4a557abe
-R 42a3d0d4c63d13c26ffa7bd8f71380ed
+P c64e6a52ac79164be37fe643a4a39bd187af198a379410def8b8419f7c2224d4
+R cd02d0fb58628c824a2d7de7efc47b02
 U stephan
-Z 5906c49c68c9155fc27b7d9430c5551e
+Z 6ab46f9c79559c9df9412a6d1bef3261
 # Remove this line to create a well-formed Fossil manifest.

diff --git a/manifest.uuid b/manifest.uuid
index 684bcd68e8542cbc957885069ac0e9ddbe947001..0fe79c981a4f2329a4defbdd11ba0b07ec07af5f 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-c64e6a52ac79164be37fe643a4a39bd187af198a379410def8b8419f7c2224d4
\ No newline at end of file
+33d1780b43182d2574adbc1928707af825c485c99762738e58bc6d7c6c52ac6a
\ No newline at end of file