26 lines
1.3 KiB
Plaintext
26 lines
1.3 KiB
Plaintext
\b;Instruction \c;synchronized\n; (for specialists)
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A \l;class\u cbot\class; method can be declared \c;synchronized\n;. This is to make sure that the method is never being executed by more than one bot at the same time.
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The following example illustrates the problem:
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\c;
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\s;class blocking
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\s;{
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\s; static int nb = 33;
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\s; synchronized int inc( )
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\s; {
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\s; int val = nb;
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\s; wait ( 2 ); // wait 2 sec.
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\s; nb = nb + 1;
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\s; return val;
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\s; }
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\s;}
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\n;
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What happens if two bots execute the \c;inc\n; method at the same time¦?
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Both of them will execute \c;val=nb\n; and wait 2 seconds so both of them will have \c;val=33\n;. With \c;synchronized\n; the first bot starts execution with \c;val=33\n; and then waits 2 seconds and returns. Only once the first bot has returned from the \c;inc\n; method, the second bot will be allowed to enter the \c;inc\n; method and therefore the second bot will always have \c;val=34\n;.
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You can have more than one synchronized method in your \l;class\u cbot\class; in order to prevent simultaneous execution across more than one method. In other words: as long as a bot's program is inside a synchronized method, no other bot can enter any synchronized method of the same class.
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\t;See also
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\c;\l;class\u cbot\class;\n;, \c;\l;static\u cbot\static;\n;
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\l;Programming\u cbot;, \l;types\u cbot\type; and \l;categories\u cbot\category;.
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