Merge pull request #6 from jsc0218/dev_gc

Dev gc

Author: jsc0218

.gitignore

@@ -4,5 +4,6 @@
 *.bc
 .cproject
 .project
+.vscode
 .*.swp
 .*.swo

Makefile

@@ -14,4 +14,4 @@ PGXS := $(shell $(PG_CONFIG) --pgxs)
 include $(PGXS)
 
 src/kv_storage.bc:
-	$(COMPILE.cxx.bc) $(CCFLAGS) $(CPPFLAGS) -fPIC -c -o $@ src/kv_storage.cc
+	$(COMPILE.cxx.bc) $(CCFLAGS) $(CPPFLAGS) -fPIC -c -o $@ src/kv_storage.cc

README.md

@@ -67,7 +67,9 @@ We test this foreign data wrapper on Ubuntu Server 18.04 using PostgreSQL-11 tog
 
 Before using this foreign data wrapper, you need to add it to ```shared_preload_libraries``` in your ```postgresql.conf``` 
 
+```sh
     shared_preload_libraries = 'kv_fdw'    # (change requires restart)
+```    
 
 and restart Postgres:
 
@@ -82,33 +84,33 @@ A simple example is as follows.
 
 
 ```
-CREATE DATABASE kvtest;  
-\c kvtest  
+    CREATE DATABASE kvtest;  
+    \c kvtest  
 
-CREATE EXTENSION kv_fdw;  
-CREATE SERVER kv_server FOREIGN DATA WRAPPER kv_fdw;  
+    CREATE EXTENSION kv_fdw;  
+    CREATE SERVER kv_server FOREIGN DATA WRAPPER kv_fdw;  
 
-CREATE FOREIGN TABLE test(key TEXT, value TEXT) SERVER kv_server;  
+    CREATE FOREIGN TABLE test(key TEXT, value TEXT) SERVER kv_server;  
 
-INSERT INTO test VALUES('YC', 'VidarDB');  
-SELECT * FROM test;  
+    INSERT INTO test VALUES('YC', 'VidarDB');  
+    SELECT * FROM test;  
 
-INSERT INTO test VALUES('California', 'Waterloo');  
-SELECT * FROM test;  
+    INSERT INTO test VALUES('California', 'Waterloo');  
+    SELECT * FROM test;  
 
-DELETE FROM test WHERE key='California';  
-SELECT * FROM test;  
+    DELETE FROM test WHERE key='California';  
+    SELECT * FROM test;  
 
-UPDATE test SET value='VidarSQL';  
-SELECT * FROM test;  
+    UPDATE test SET value='VidarSQL';  
+    SELECT * FROM test;  
 
-DROP FOREIGN TABLE test;  
+    DROP FOREIGN TABLE test;  
 
-DROP SERVER kv_server;  
-DROP EXTENSION kv_fdw;  
+    DROP SERVER kv_server;  
+    DROP EXTENSION kv_fdw;  
   
-\c postgres  
-DROP DATABASE kvtest;  
+    \c postgres  
+    DROP DATABASE kvtest;  
 
 ``` 
 
@@ -118,15 +120,15 @@ We have tested certain typical SQL statements and will add more test cases later
 
 
 ```sh
-sudo service postgresql restart  
+    sudo service postgresql restart  
 
-cd PostgresForeignDataWrapper
+    cd PostgresForeignDataWrapper
 
-sudo -u postgres psql -U postgres -a -f test/sql/create.sql 
+    sudo -u postgres psql -U postgres -a -f test/sql/create.sql 
 
-sudo -u postgres psql -U postgres -d kvtest -a -f test/sql/test.sql 
+    sudo -u postgres psql -U postgres -d kvtest -a -f test/sql/test.sql 
 
-sudo -u postgres psql -U postgres -d kvtest -a -f test/sql/clear.sql  
+    sudo -u postgres psql -U postgres -d kvtest -a -f test/sql/clear.sql  
 ```
 
 # Debug 
@@ -135,7 +137,7 @@ If you want to debug the source code, you may need to start PostgreSQL in the de
 
 
 ```sh
-sudo service postgresql stop  
+    sudo service postgresql stop  
 
-sudo -u postgres /usr/lib/postgresql/11/bin/postgres -d 0 -D /var/lib/postgresql/11/main -c config_file=/etc/postgresql/11/main/postgresql.conf
+    sudo -u postgres /usr/lib/postgresql/11/bin/postgres -d 0 -D /var/lib/postgresql/11/main -c config_file=/etc/postgresql/11/main/postgresql.conf
 ```  

src/kv_fdw.c

@@ -26,7 +26,6 @@ PG_FUNCTION_INFO_V1(kv_fdw_validator);
 
 static SharedMem *ptr = NULL;  // in client process
 
-
 static void GetForeignRelSize(PlannerInfo *root,
                               RelOptInfo *baserel,
                               Oid foreignTableId) {

src/kv_fdw.h

@@ -12,12 +12,45 @@
 #include "access/attnum.h"
 #include "utils/relcache.h"
 
+/* Defines */
+#define KVKEYJUNK "__key_junk"
+
+#define KVFDWNAME "kv_fdw"
+
+#define BACKFILE "/KVSharedMem"
+
+#define PERMISSION 0777
+
+#define PATHMAXLENGTH 4096
+
+#define BUFSIZE 65536
+
+#define FILENAMELENGTH 20
+
+#define RESPONSEFILE "/KVSharedResponse"
+
+#define RESPONSEQUEUELENGTH 2
+
+#define DATAAREASIZE sizeof(char)*BUFSIZE
 
+
+/* Shared memory for function requests: 
+ * mutex is used for the mutual exclusion of the request buffer;
+ * full is used to tell whether the request buffer is full;
+ * agent[2] are used to synchronize the creation of the worker process;
+ * worker is used to notify the worker process after a request is submitted;
+ * responseMutexes[RESPONSEQUEUELENGTH] are used for the mutual exclusion of the response buffer;
+ * responseSync[RESPONSEQUEUELENGTH] are used to notify child processes after the response is ready.
+ */
 typedef struct SharedMem {
+    sem_t mutex;
+    sem_t full;
     sem_t agent[2];
-    sem_t worker[2];
+    sem_t worker;
+    sem_t responseMutexes[RESPONSEQUEUELENGTH];
+    sem_t responseSync[RESPONSEQUEUELENGTH];
     bool workerProcessCreated;
-    char area[65536];  // assume ~64K for a tuple is enough
+    char area[BUFSIZE];  // assume ~64K for a tuple is enough
 } SharedMem;
 
 /* Holds the option values to be used when reading or writing files.
@@ -67,18 +100,6 @@ typedef enum FuncName {
 } FuncName;
 
 
-/* Defines */
-#define KVKEYJUNK "__key_junk"
-
-#define KVFDWNAME "kv_fdw"
-
-#define BACKFILE "/KVSharedMem"
-
-#define PERMISSION 0777
-
-#define PATHMAXLENGTH 4096
-
-
 /* Function declarations for extension loading and unloading */
 extern void _PG_init(void);
 

src/kv_posix.c

@@ -113,3 +113,11 @@ void SemWait(sem_t *__sem, const char *fun) {
         ereport(ERROR, (errmsg("%s %s failed", fun, __func__)));
     }
 }
+
+int SemTryWait(sem_t *__sem, const char *fun) {
+    int ret = sem_trywait(__sem);
+    if (ret == -1 && errno != EAGAIN) {
+        ereport(ERROR, (errmsg("%s %s failed", fun, __func__)));
+    }
+    return ret;
+}

src/kv_posix.h

@@ -73,5 +73,6 @@ extern void SemPost(sem_t *__sem, const char *fun);
 
 extern void SemWait(sem_t *__sem, const char *fun);
 
+extern int SemTryWait(sem_t *__sem, const char *fun);
 
 #endif