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b5f27035 FT |
1 | package dolda.jsvc; |
2 | ||
3 | import java.util.*; | |
4 | ||
5 | public class ContextParam<T> { | |
6 | private boolean bound; | |
7 | private T value; | |
8 | private final Object id = new Object(); | |
9 | private Map<ThreadContext, T> perctx = new WeakHashMap<ThreadContext, T>(); | |
10 | private Map<Thread, T> perthr = new WeakHashMap<Thread, T>(); | |
11 | ||
12 | public ContextParam(T def) { | |
13 | this.value = def; | |
14 | this.bound = true; | |
15 | } | |
16 | ||
17 | public ContextParam() { | |
18 | this.bound = false; | |
19 | } | |
20 | ||
21 | public synchronized T get() { | |
22 | Thread th = Thread.currentThread(); | |
23 | if(perthr.containsKey(th)) | |
24 | return(perthr.get(th)); | |
4b8346e1 | 25 | ThreadContext ctx = ThreadContext.current(); |
b5f27035 FT |
26 | if(perctx.containsKey(ctx)) |
27 | return(perctx.get(ctx)); | |
28 | if(!bound) | |
29 | throw(new IllegalStateException("No value is bound to this parameter.")); | |
30 | return(value); | |
31 | } | |
32 | ||
33 | public synchronized T ctxset(T val) { | |
4b8346e1 | 34 | ThreadContext ctx = ThreadContext.current(); |
b5f27035 FT |
35 | return(perctx.put(ctx, val)); |
36 | } | |
37 | ||
b5f27035 FT |
38 | public static Responder let(final Responder next, Object... params) { |
39 | final Map<ContextParam, Object> values = new HashMap<ContextParam, Object>(); | |
40 | if((params.length % 2) != 0) | |
41 | throw(new IllegalArgumentException("SvcConfig.let takes only an even number of parameters")); | |
42 | for(int i = 0; i < params.length; i += 2) | |
43 | values.put((ContextParam)params[i], params[i + 1]); | |
44 | ||
45 | return(new Responder() { | |
46 | /* This can very well actually be set to something | |
47 | * of the wrong type, but since the result would, | |
48 | * obviously, be a ClassCastException either way, | |
49 | * this way is at least the more convenient. */ | |
50 | @SuppressWarnings("unchecked") | |
51 | public void respond(Request req) { | |
52 | final Map<ContextParam, Object> old = new HashMap<ContextParam, Object>(); | |
53 | Thread th = Thread.currentThread(); | |
54 | for(Map.Entry<ContextParam, Object> val : values.entrySet()) { | |
55 | ContextParam p = val.getKey(); | |
56 | synchronized(p) { | |
57 | if(p.perthr.containsKey(th)) | |
58 | old.put(p, p.perthr.get(th)); | |
59 | p.perthr.put(th, val.getValue()); | |
60 | } | |
61 | } | |
62 | try { | |
63 | next.respond(req); | |
64 | } finally { | |
65 | for(Map.Entry<ContextParam, Object> val : values.entrySet()) { | |
66 | ContextParam p = val.getKey(); | |
67 | synchronized(p) { | |
68 | if(old.containsKey(p)) { | |
69 | p.perthr.put(th, old.get(p)); | |
70 | } else { | |
71 | p.perthr.remove(th); | |
72 | } | |
73 | } | |
74 | } | |
75 | } | |
76 | } | |
77 | }); | |
78 | } | |
79 | } |