Java example source code file (SynchronizedStatement.java)

This example Java source code file (SynchronizedStatement.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

assembler, checkcontext, codecontext, context, expression, hashtable, integer, label, localmember, statement, synchronizedstatement, trydata, type, util, vset

The SynchronizedStatement.java Java example source code

/*
 * Copyright (c) 1994, 2003, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.tools.tree;

import sun.tools.java.*;
import sun.tools.asm.Assembler;
import sun.tools.asm.Label;
import sun.tools.asm.TryData;
import sun.tools.asm.CatchData;
import java.io.PrintStream;
import java.util.Hashtable;

/**
 * WARNING: The contents of this source file are not part of any
 * supported API.  Code that depends on them does so at its own risk:
 * they are subject to change or removal without notice.
 */
public
class SynchronizedStatement extends Statement {
    Expression expr;
    Statement body;
    boolean needReturnSlot;   // set by inner return statement

    /**
     * Constructor
     */
    public SynchronizedStatement(long where, Expression expr, Statement body) {
        super(SYNCHRONIZED, where);
        this.expr = expr;
        this.body = body;
    }

    /**
     * Check statement
     */
    Vset check(Environment env, Context ctx, Vset vset, Hashtable exp) {
        checkLabel(env, ctx);
        CheckContext newctx = new CheckContext(ctx, this);
        vset = reach(env, vset);
        vset = expr.checkValue(env, newctx, vset, exp);
        if (expr.type.equals(Type.tNull)) {
            env.error(expr.where, "synchronized.null");
        }
        expr = convert(env, newctx, Type.tClass(idJavaLangObject), expr);
        vset = body.check(env, newctx, vset, exp);
        return ctx.removeAdditionalVars(vset.join(newctx.vsBreak));
    }

    /**
     * Inline
     */
    public Statement inline(Environment env, Context ctx) {
        if (body != null) {
            body = body.inline(env, ctx);
        }
        expr = expr.inlineValue(env, ctx);
        return this;
    }

    /**
     * Create a copy of the statement for method inlining
     */
    public Statement copyInline(Context ctx, boolean valNeeded) {
        SynchronizedStatement s = (SynchronizedStatement)clone();
        s.expr = expr.copyInline(ctx);
        if (body != null) {
            s.body = body.copyInline(ctx, valNeeded);
        }
        return s;
    }

    /**
     * Compute cost of inlining this statement
     */
    public int costInline(int thresh, Environment env, Context ctx){
        int cost = 1;
        if (expr != null) {
            cost += expr.costInline(thresh, env,ctx);
            if (cost >= thresh) return cost;
        }
        if (body != null) {
            cost += body.costInline(thresh, env,ctx);
        }
        return cost;
    }

    /**
     * Code
     */
    public void code(Environment env, Context ctx, Assembler asm) {
        ClassDefinition clazz = ctx.field.getClassDefinition();
        expr.codeValue(env, ctx, asm);
        ctx = new Context(ctx);

        if (needReturnSlot) {
            Type returnType = ctx.field.getType().getReturnType();
            LocalMember localfield = new LocalMember(0, clazz, 0, returnType,
                                                   idFinallyReturnValue);
            ctx.declare(env, localfield);
            env.debugOutput("Assigning return slot to " + localfield.number);
        }

        LocalMember f1 = new LocalMember(where, clazz, 0, Type.tObject, null);
        LocalMember f2 = new LocalMember(where, clazz, 0, Type.tInt, null);
        Integer num1 = new Integer(ctx.declare(env, f1));
        Integer num2 = new Integer(ctx.declare(env, f2));

        Label endLabel = new Label();

        TryData td = new TryData();
        td.add(null);

        // lock the object
        asm.add(where, opc_astore, num1);
        asm.add(where, opc_aload, num1);
        asm.add(where, opc_monitorenter);

        // Main body
        CodeContext bodyctx = new CodeContext(ctx, this);
        asm.add(where, opc_try, td);
        if (body != null) {
            body.code(env, bodyctx, asm);
        } else {
            asm.add(where, opc_nop);
        }
        asm.add(bodyctx.breakLabel);
        asm.add(td.getEndLabel());

        // Cleanup afer body
        asm.add(where, opc_aload, num1);
        asm.add(where, opc_monitorexit);
        asm.add(where, opc_goto, endLabel);

        // Catch code
        CatchData cd = td.getCatch(0);
        asm.add(cd.getLabel());
        asm.add(where, opc_aload, num1);
        asm.add(where, opc_monitorexit);
        asm.add(where, opc_athrow);

        // Final body
        asm.add(bodyctx.contLabel);
        asm.add(where, opc_astore, num2);
        asm.add(where, opc_aload, num1);
        asm.add(where, opc_monitorexit);
        asm.add(where, opc_ret, num2);

        asm.add(endLabel);
    }

    /**
     * Print
     */
    public void print(PrintStream out, int indent) {
        super.print(out, indent);
        out.print("synchronized ");
        expr.print(out);
        out.print(" ");
        if (body != null) {
            body.print(out, indent);
        } else {
            out.print("{}");
        }
    }
}