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<HTML><HEAD><META http-equiv="Content-Type" content="text/html; charset=UTF-8"><TITLE>Perst.IResource.SharedLock</TITLE><LINK REL=STYLESHEET HREF="../CommentReport.css" TYPE="text/css"></HEAD><BODY topmargin=0 rightmargin=0 leftmargin=0 style="background-image: url(../titletile.jpg); background-repeat:repeat-x; background-position: 0 0;" ><DIV CLASS="PageHeading">Perst.IResource.SharedLock Function</DIV><DIV CLASS="Description">
Lock persistent object in shared mode. Other threads will be able to set their
shared locks on this objects, but not exclusive lock can be set until this lock is released.
Upgrading of the lock is not possible (thread having read lock can not upgrade it to exclusive lock).
It is done to prevent possible deadlocks caused by lock updates.
But locks are reentrant - so thread can request the same lock many times (and correspondent
number of unlocks is needed to release the lock).
Locking the object doesn't prevent other threads from accessing the object -
it only has influence on <code>sharedLock</code> and <code>exclusiveLock</code> methods.
So programmer should set proper lock before accessing the object in multithreaded application.
If object is concurrently accessed by several threads in read-only mode, then explicit locking
of this object is not needed, because language API provides consistent retrieving of objects itself.
Only persistent object (object which were assigned to the the storage either implicitly by
saving some other persistent object referencing this object, either explicitly by
<code>Storage.makeObjectPersistent</code> method.
<P></DIV><IMG src="../GradLeft.jpg" width=7 height=378 alt="" border="0" style="position:absolute; left:10; top:18;z-Index:2"><IMG src="../GradTop.jpg" width=352 height=7 alt="" border="0" align="top" style="position:absolute; left:10; top:18; z-index:1"><DIV CLASS="Remarks"><SPAN CLASS="RemarkHdrX">Public void SharedLock ()</SPAN></DIV><TABLE CLASS="InfoTable" cellpadding=0 cellspacing=0><TR height=20><TD width=20> </TD><TD valign=top align=left width=9 bgcolor="#cccc66"><IMG SRC="../graycorner.jpg" align=top></TD><TD CLASS="TableLightLabel" WIDTH=206>Return</TD><TD CLASS="TableLightLabel" >Description</TD><TD width=20> </TD></TR><TR height=20><TD width=20> </TD><TD CLASS="TableLightDesc"> </TD><TD CLASS="TableLightDesc">void</TD><TD CLASS="TableLightDesc"> </TD><TD width=20> </TD></TR></TABLE><DIV CLASS="RemarkHdr"><B>Other overloads:</B><BR></DIV><DIV CLASS="Remarks">Perst.IResource.SharedLock(3)</DIV></BODY></HTML>⌨️ 快捷键说明
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