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< p > Library Version 11.2.5.2< / p >
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< th colspan = "3" align = "center" > DbEnv::lock_detect()< / th >
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The DbLock Handle
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< h2 class = "title" style = "clear: both" > < a id = "lockdetect" > < / a > DbEnv::lock_detect()< / h2 >
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< pre class = "programlisting" > #include < db_cxx.h>
int
DbEnv::lock_detect(u_int32_t flags, u_int32_t atype, int *rejected);< / pre >
< p >
The < code class = "methodname" > DbEnv::lock_detect()< / code > method runs one iteration of the deadlock
detector. The deadlock detector traverses the lock table and marks one
of the participating lock requesters for rejection in each deadlock it
finds.
< / p >
< p >
The < code class = "methodname" > DbEnv::lock_detect()< / code > < span >
< span >
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
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< h3 class = "title" > < a id = "id3614184" > < / a > Parameters< / h3 >
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< h4 class = "title" > < a id = "id3614194" > < / a > flags< / h4 >
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The < span class = "bold" > < strong > flags< / strong > < / span > parameter is currently
unused, and must be set to 0.
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< h4 class = "title" > < a id = "id3613817" > < / a > atype< / h4 >
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The < span class = "bold" > < strong > atype< / strong > < / span > parameter specifies which
lock request(s) to reject. The deadlock detector will reject the lock
request with the lowest priority. If multiple lock requests have the
lowest priority, then the < span class = "bold" > < strong > atype< / strong > < / span >
parameter is used to select which of those lock requests to reject.
It must be set to one of the following list:
< / p >
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< p > < a id = "detect_DB_LOCK_DEFAULT" > < / a >
< code class = "literal" > DB_LOCK_DEFAULT< / code >
< / p >
< p >
Use the default lock policy, which is DB_LOCK_RANDOM.
< / p >
< / li >
< li >
< p > < a id = "detect_DB_LOCK_EXPIRE" > < / a >
< code class = "literal" > DB_LOCK_EXPIRE< / code >
< / p >
< p >
Reject lock requests which have timed out. No other deadlock
detection is performed.
< / p >
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< li >
< p > < a id = "detect_DB_LOCK_MAXLOCKS" > < / a >
< code class = "literal" > DB_LOCK_MAXLOCKS< / code >
< / p >
< p >
Reject the lock request for the locker ID with the most locks.
< / p >
< / li >
< li >
< p > < a id = "detect_DB_LOCK_MAXWRITE" > < / a >
< code class = "literal" > DB_LOCK_MAXWRITE< / code >
< / p >
< p >
Reject the lock request for the locker ID with the most write locks.
< / p >
< / li >
< li >
< p > < a id = "detect_DB_LOCK_MINLOCKS" > < / a >
< code class = "literal" > DB_LOCK_MINLOCKS< / code >
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< p >
Reject the lock request for the locker ID with the fewest locks.
< / p >
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< p > < a id = "detect_DB_LOCK_MINWRITE" > < / a >
< code class = "literal" > DB_LOCK_MINWRITE< / code >
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< p >
Reject the lock request for the locker ID with the fewest write locks.
< / p >
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< p > < a id = "detect_DB_LOCK_OLDEST" > < / a >
< code class = "literal" > DB_LOCK_OLDEST< / code >
< / p >
< p >
Reject the lock request for the locker ID with the oldest lock.
< / p >
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< li >
< p > < a id = "detect_DB_LOCK_RANDOM" > < / a >
< code class = "literal" > DB_LOCK_RANDOM< / code >
< / p >
< p >
Reject the lock request for a random locker ID.
< / p >
< / li >
< li >
< p > < a id = "detect_DB_LOCK_YOUNGEST" > < / a >
< code class = "literal" > DB_LOCK_YOUNGEST< / code >
< / p >
< p >
Reject the lock request for the locker ID with the youngest lock.
< / p >
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< h4 class = "title" > < a id = "id3614451" > < / a > rejected< / h4 >
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If the < span class = "bold" > < strong > rejected< / strong > < / span > parameter is
non-NULL, the memory location to which it refers will be set to the
number of lock requests that were rejected.
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< h3 class = "title" > < a id = "id3613870" > < / a > Errors< / h3 >
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The < code class = "methodname" > DbEnv::lock_detect()< / code > < span >
< span >
method may fail and throw a < a class = "link" href = "dbexception.html" title = "Chapter > DbException< / a >
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
< / span >
< / span >
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< h4 class = "title" > < a id = "id3614419" > < / a > EINVAL< / h4 >
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An invalid flag value or parameter was specified.
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< a class = "link" href = "env.html" title = "Chapter > DbEnv< / a > , < a class = "link" href = "lock.html" title = "Chapter > DbLock< / a >
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< h3 class = "title" > < a id = "id3614254" > < / a > See Also< / h3 >
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< a class = "xref" href = "lock.html#locklist" title = "Locking Subsystem and Related Methods" > Locking Subsystem and Related Methods< / a >
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