issue 1350: TestCrashAPI: PageStore.freeListPagesPerList

this looks like some kind of race condition where we are attempting to compact a PageStore which has not been properly opened yet.
Various places in Database are touching the pageStore without being synchronized, so fix those and lets see if that helps

h2/src/main/org/h2/engine/Database.java

@@ -549,6 +549,7 @@ public class Database implements DataHandler {
                 if (store != null) {
                     store.closeImmediately();
                 }
+                synchronized(this) {
                     if (pageStore != null) {
                         try {
                             pageStore.close();
@@ -557,6 +558,7 @@ public class Database implements DataHandler {
                         }
                         pageStore = null;
                     }
+                }
                 if (lock != null) {
                     stopServer();
                     if (fileLockMethod != FileLockMethod.SERIALIZED) {
@@ -2664,6 +2666,7 @@ public class Database implements DataHandler {
             }
             return null;
         }
+        synchronized (this) {
             if (pageStore == null) {
                 pageStore = new PageStore(this, databaseName +
                         Constants.SUFFIX_PAGE_FILE, accessModeData, cacheSize);
@@ -2678,6 +2681,7 @@ public class Database implements DataHandler {
             }
             return pageStore;
         }
+    }
 
     /**
      * Get the first user defined table, excluding the LOB_BLOCKS table that the
@@ -2925,6 +2929,11 @@ public class Database implements DataHandler {
         if (log < 0 || log > 2) {
             throw DbException.getInvalidValueException("LOG", log);
         }
+        if (store != null) {
+            this.logMode = log;
+            return;
+        }
+        synchronized (this) {
             if (pageStore != null) {
                 if (log != PageStore.LOG_MODE_SYNC ||
                         pageStore.getLogMode() != PageStore.LOG_MODE_SYNC) {
@@ -2935,17 +2944,17 @@ public class Database implements DataHandler {
                 this.logMode = log;
                 pageStore.setLogMode(log);
             }
-        if (store != null) {
-            this.logMode = log;
         }
     }
 
     public int getLogMode() {
+        if (store != null) {
+            return logMode;
+        }
+        synchronized (this) {
             if (pageStore != null) {
                 return pageStore.getLogMode();
             }
-        if (store != null) {
-            return logMode;
         }
         return PageStore.LOG_MODE_OFF;
     }