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<TITLE>VecLockWriteSet_Private</TITLE>
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<div id="version" align=right><b>petsc-3.14.5 2021-03-03</b></div>
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<A NAME="VecLockWriteSet_Private"><H1>VecLockWriteSet_Private</H1></A>
Lock or unlock a vector for exclusive read/write access
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscvec.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../Vec/VecLockWriteSet_Private.html#VecLockWriteSet_Private">VecLockWriteSet_Private</A>(<A HREF="../Vec/Vec.html#Vec">Vec</A> x,<A HREF="../Sys/PetscBool.html#PetscBool">PetscBool</A> flg)
</PRE>
Logically Collective on <A HREF="../Vec/Vec.html#Vec">Vec</A>
<P>
<H3><FONT COLOR="#CC3333">Input Parameter</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>x </B></TD><TD>- the vector
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>flg </B></TD><TD>- <A HREF="../Sys/PETSC_TRUE.html#PETSC_TRUE">PETSC_TRUE</A> to lock the vector for writing; <A HREF="../Sys/PETSC_FALSE.html#PETSC_FALSE">PETSC_FALSE</A> to unlock it.
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
The function is usefull in split-phase computations, which usually have a begin phase and an end phase.
One can call <A HREF="../Vec/VecLockWriteSet_Private.html#VecLockWriteSet_Private">VecLockWriteSet_Private</A>(x,<A HREF="../Sys/PETSC_TRUE.html#PETSC_TRUE">PETSC_TRUE</A>) in the begin phase to lock a vector for exclusive
access, and call <A HREF="../Vec/VecLockWriteSet_Private.html#VecLockWriteSet_Private">VecLockWriteSet_Private</A>(x,<A HREF="../Sys/PETSC_FALSE.html#PETSC_FALSE">PETSC_FALSE</A>) in the end phase to unlock the vector from exclusive
access. In this way, one is ensured no other operations can access the vector in between. The code may like
<P>
<P>
<A HREF="../Vec/VecGetArray.html#VecGetArray">VecGetArray</A>(x,&xdata); // begin phase
<A HREF="../Vec/VecLockWriteSet_Private.html#VecLockWriteSet_Private">VecLockWriteSet_Private</A>(v,<A HREF="../Sys/PETSC_TRUE.html#PETSC_TRUE">PETSC_TRUE</A>);
<P>
Other operations, which can not acceess x anymore (they can access xdata, of course)
<P>
<A HREF="../Vec/VecRestoreArray.html#VecRestoreArray">VecRestoreArray</A>(x,&vdata); // end phase
<A HREF="../Vec/VecLockWriteSet_Private.html#VecLockWriteSet_Private">VecLockWriteSet_Private</A>(v,<A HREF="../Sys/PETSC_FALSE.html#PETSC_FALSE">PETSC_FALSE</A>);
<P>
The call can not be nested on the same vector, in other words, one can not call <A HREF="../Vec/VecLockWriteSet_Private.html#VecLockWriteSet_Private">VecLockWriteSet_Private</A>(x,<A HREF="../Sys/PETSC_TRUE.html#PETSC_TRUE">PETSC_TRUE</A>)
again before calling <A HREF="../Vec/VecLockWriteSet_Private.html#VecLockWriteSet_Private">VecLockWriteSet_Private</A>(v,<A HREF="../Sys/PETSC_FALSE.html#PETSC_FALSE">PETSC_FALSE</A>).
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../Vec/VecRestoreArray.html#VecRestoreArray">VecRestoreArray</A>(), <A HREF="../Vec/VecGetArrayRead.html#VecGetArrayRead">VecGetArrayRead</A>(), <A HREF="../Vec/VecLockReadPush.html#VecLockReadPush">VecLockReadPush</A>(), <A HREF="../Vec/VecLockReadPop.html#VecLockReadPop">VecLockReadPop</A>(), <A HREF="../Vec/VecLockGet.html#VecLockGet">VecLockGet</A>()
<BR><P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>beginner<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/vec/vec/interface/rvector.c.html#VecLockWriteSet_Private">src/vec/vec/interface/rvector.c</A>
<BR><A HREF="./index.html">Index of all Vec routines</A>
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