Merge "Suggestions to enhance the SQL call pattern."

[gigi.git] / src / org / cacert / gigi / database / DatabaseConnection.java

diff --git a/src/org/cacert/gigi/database/DatabaseConnection.java b/src/org/cacert/gigi/database/DatabaseConnection.java
index 868f42331886ac67387f1ecf1218eaf09743db99..a855d706155faff34fd993cbbcbcf88fd0abb8c1 100644 (file)
--- a/src/org/cacert/gigi/database/DatabaseConnection.java
+++ b/src/org/cacert/gigi/database/DatabaseConnection.java
@@ -14,6 +14,7 @@ import java.util.HashSet;
 import java.util.Map.Entry;
 import java.util.Properties;
 import java.util.StringJoiner;
+import java.util.concurrent.LinkedBlockingDeque;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -21,6 +22,28 @@ import org.cacert.gigi.database.SQLFileManager.ImportType;
 
 public class DatabaseConnection {
 
+    public static class Link implements AutoCloseable {
+
+        private DatabaseConnection target;
+
+        protected Link(DatabaseConnection target) {
+            this.target = target;
+        }
+
+        @Override
+        public void close() {
+            synchronized (DatabaseConnection.class) {
+                Link i = instances.get(Thread.currentThread());
+                if (i != this) {
+                    throw new Error();
+                }
+                instances.remove(Thread.currentThread());
+                pool.add(target);
+            }
+        }
+
+    }
+
     public static final int MAX_CACHED_INSTANCES = 3;
 
     private static class StatementDescriptor {
@@ -48,7 +71,7 @@ public class DatabaseConnection {
 
         }
 
-        public PreparedStatement getTarget() {
+        public synchronized PreparedStatement getTarget() {
             return target;
         }
 
@@ -99,7 +122,7 @@ public class DatabaseConnection {
 
     }
 
-    public static final int CURRENT_SCHEMA_VERSION = 7;
+    public static final int CURRENT_SCHEMA_VERSION = 11;
 
     public static final int CONNECTION_TIMEOUT = 24 * 60 * 60;
 
@@ -107,7 +130,7 @@ public class DatabaseConnection {
 
     private HashMap<StatementDescriptor, PreparedStatement> statements = new HashMap<StatementDescriptor, PreparedStatement>();
 
-    HashSet<PreparedStatement> underUse = new HashSet<>();
+    private HashSet<PreparedStatement> underUse = new HashSet<>();
 
     private static Properties credentials;
 
@@ -183,17 +206,23 @@ public class DatabaseConnection {
         lastAction = System.currentTimeMillis();
     }
 
-    private static DatabaseConnection instance;
+    private static HashMap<Thread, Link> instances = new HashMap<>();
 
-    public static DatabaseConnection getInstance() {
-        if (instance == null) {
-            synchronized (DatabaseConnection.class) {
-                if (instance == null) {
-                    instance = new DatabaseConnection();
-                }
-            }
+    private static LinkedBlockingDeque<DatabaseConnection> pool = new LinkedBlockingDeque<>();
+
+    private static int connCount = 0;
+
+    public static synchronized DatabaseConnection getInstance() {
+        Link l = instances.get(Thread.currentThread());
+        if (l == null) {
+            throw new Error("No database connection allocated");
         }
-        return instance;
+        return l.target;
+    }
+
+    public static synchronized boolean hasInstance() {
+        Link l = instances.get(Thread.currentThread());
+        return l != null;
     }
 
     public static boolean isInited() {
@@ -205,24 +234,24 @@ public class DatabaseConnection {
             throw new Error("Re-initiaizing is forbidden.");
         }
         credentials = conf;
-        int version = 0;
-        try (GigiPreparedStatement gigiPreparedStatement = new GigiPreparedStatement("SELECT version FROM \"schemeVersion\" ORDER BY version DESC LIMIT 1;")) {
-            GigiResultSet rs = gigiPreparedStatement.executeQuery();
-            if (rs.next()) {
-                version = rs.getInt(1);
+        try (Link i = newLink(false)) {
+            int version = 0;
+            try (GigiPreparedStatement gigiPreparedStatement = new GigiPreparedStatement("SELECT version FROM \"schemeVersion\" ORDER BY version DESC LIMIT 1;")) {
+                GigiResultSet rs = gigiPreparedStatement.executeQuery();
+                if (rs.next()) {
+                    version = rs.getInt(1);
+                }
             }
+            if (version == CURRENT_SCHEMA_VERSION) {
+                return; // Good to go
+            }
+            if (version > CURRENT_SCHEMA_VERSION) {
+                throw new Error("Invalid database version. Please fix this.");
+            }
+            upgrade(version);
+        } catch (InterruptedException e) {
+            throw new Error(e);
         }
-        if (version == CURRENT_SCHEMA_VERSION) {
-            return; // Good to go
-        }
-        if (version > CURRENT_SCHEMA_VERSION) {
-            throw new Error("Invalid database version. Please fix this.");
-        }
-        upgrade(version);
-    }
-
-    public void beginTransaction() throws SQLException {
-        c.setAutoCommit(false);
     }
 
     private static void upgrade(int version) {
@@ -230,12 +259,7 @@ public class DatabaseConnection {
             Statement s = getInstance().c.createStatement();
             try {
                 while (version < CURRENT_SCHEMA_VERSION) {
-                    try (InputStream resourceAsStream = DatabaseConnection.class.getResourceAsStream("upgrade/from_" + version + ".sql")) {
-                        if (resourceAsStream == null) {
-                            throw new Error("Upgrade script from version " + version + " was not found.");
-                        }
-                        SQLFileManager.addFile(s, resourceAsStream, ImportType.PRODUCTION);
-                    }
+                    addUpgradeScript(Integer.toString(version), s);
                     version++;
                 }
                 s.addBatch("UPDATE \"schemeVersion\" SET version='" + version + "'");
@@ -252,19 +276,12 @@ public class DatabaseConnection {
         }
     }
 
-    public void commitTransaction() throws SQLException {
-        c.commit();
-        c.setAutoCommit(true);
-    }
-
-    public void quitTransaction() {
-        try {
-            if ( !c.getAutoCommit()) {
-                c.rollback();
-                c.setAutoCommit(true);
+    private static void addUpgradeScript(String version, Statement s) throws Error, IOException, SQLException {
+        try (InputStream resourceAsStream = DatabaseConnection.class.getResourceAsStream("upgrade/from_" + version + ".sql")) {
+            if (resourceAsStream == null) {
+                throw new Error("Upgrade script from version " + version + " was not found.");
             }
-        } catch (SQLException e) {
-            e.printStackTrace();
+            SQLFileManager.addFile(s, resourceAsStream, ImportType.PRODUCTION);
         }
     }
 
@@ -313,7 +330,7 @@ public class DatabaseConnection {
         return underUse.size();
     }
 
-    public void lockedStatements(PrintWriter writer) {
+    public synchronized void lockedStatements(PrintWriter writer) {
         writer.println(underUse.size());
         for (PreparedStatement ps : underUse) {
             for (Entry<StatementDescriptor, PreparedStatement> e : statements.entrySet()) {
@@ -326,4 +343,23 @@ public class DatabaseConnection {
             }
         }
     }
+
+    public static synchronized Link newLink(boolean readOnly) throws InterruptedException {
+        if (instances.get(Thread.currentThread()) != null) {
+            throw new Error("There is already a connection allocated for this thread.");
+        }
+        if (pool.isEmpty() && connCount < 5) {
+            pool.addLast(new DatabaseConnection());
+            connCount++;
+        }
+        DatabaseConnection conn = pool.takeFirst();
+        try {
+            conn.c.setReadOnly(readOnly);
+        } catch (SQLException e) {
+            throw new Error(e);
+        }
+        Link l = new Link(conn);
+        instances.put(Thread.currentThread(), l);
+        return l;
+    }
 }