X-Git-Url: http://git.dolda2000.com/gitweb/?a=blobdiff_plain;f=src%2Fdolda%2Fjsvc%2FContextParam.java;fp=src%2Fdolda%2Fjsvc%2FContextParam.java;h=f146dc385a80f83ae34d60cead99c35ad2c77dcd;hb=b5f270350bfadea58c6b14516422df00202e9d46;hp=0000000000000000000000000000000000000000;hpb=a0b186f8f8342791c1d65ca8f04118b0d73d5bb8;p=jsvc.git

diff --git a/src/dolda/jsvc/ContextParam.java b/src/dolda/jsvc/ContextParam.java
new file mode 100644
index 0000000..f146dc3
--- /dev/null
+++ b/src/dolda/jsvc/ContextParam.java
@@ -0,0 +1,87 @@
+package dolda.jsvc;
+
+import java.util.*;
+
+public class ContextParam<T> {
+    private boolean bound;
+    private T value;
+    private final Object id = new Object();
+    private Map<ThreadContext, T> perctx = new WeakHashMap<ThreadContext, T>();
+    private Map<Thread, T> perthr = new WeakHashMap<Thread, T>();
+	
+    public ContextParam(T def) {
+	this.value = def;
+	this.bound = true;
+    }
+	
+    public ContextParam() {
+	this.bound = false;
+    }
+	
+    public synchronized T get() {
+	Thread th = Thread.currentThread();
+	if(perthr.containsKey(th))
+	    return(perthr.get(th));
+	ThreadContext ctx = getctx();
+	if(perctx.containsKey(ctx))
+	    return(perctx.get(ctx));
+	if(!bound)
+	    throw(new IllegalStateException("No value is bound to this parameter."));
+	return(value);
+    }
+	
+    public synchronized T ctxset(T val) {
+	ThreadContext ctx = getctx();
+	return(perctx.put(ctx, val));
+    }
+    
+    private static ThreadContext getctx() {
+	for(ThreadGroup tg = Thread.currentThread().getThreadGroup(); tg != null; tg = tg.getParent()) {
+	    if(tg instanceof ThreadContext)
+		return((ThreadContext)tg);
+	}
+	return(null);
+    }
+    
+    public static Responder let(final Responder next, Object... params) {
+	final Map<ContextParam, Object> values = new HashMap<ContextParam, Object>();
+	if((params.length % 2) != 0)
+	    throw(new IllegalArgumentException("SvcConfig.let takes only an even number of parameters"));
+	for(int i = 0; i < params.length; i += 2)
+	    values.put((ContextParam)params[i], params[i + 1]);
+	
+	return(new Responder() {
+		/* This can very well actually be set to something
+		 * of the wrong type, but since the result would,
+		 * obviously, be a ClassCastException either way,
+		 * this way is at least the more convenient. */
+		@SuppressWarnings("unchecked")
+		public void respond(Request req) {
+		    final Map<ContextParam, Object> old = new HashMap<ContextParam, Object>();
+		    Thread th = Thread.currentThread();
+		    for(Map.Entry<ContextParam, Object> val : values.entrySet()) {
+			ContextParam p = val.getKey();
+			synchronized(p) {
+			    if(p.perthr.containsKey(th))
+				old.put(p, p.perthr.get(th));
+			    p.perthr.put(th, val.getValue());
+			}
+		    }
+		    try {
+			next.respond(req);
+		    } finally {
+			for(Map.Entry<ContextParam, Object> val : values.entrySet()) {
+			    ContextParam p = val.getKey();
+			    synchronized(p) {
+				if(old.containsKey(p)) {
+				    p.perthr.put(th, old.get(p));
+				} else {
+				    p.perthr.remove(th);
+				}
+			    }
+			}
+		    }
+		}
+	    });
+    }
+}