diff options
Diffstat (limited to 'docs/tutorials/013/combine.shar')
| -rw-r--r-- | docs/tutorials/013/combine.shar | 661 |
1 files changed, 0 insertions, 661 deletions
diff --git a/docs/tutorials/013/combine.shar b/docs/tutorials/013/combine.shar deleted file mode 100644 index feedd51e0a8..00000000000 --- a/docs/tutorials/013/combine.shar +++ /dev/null @@ -1,661 +0,0 @@ -#!/bin/sh -# This is a shell archive (produced by GNU sharutils 4.2). -# To extract the files from this archive, save it to some FILE, remove -# everything before the `!/bin/sh' line above, then type `sh FILE'. -# -# Made on 1999-01-31 11:54 EST by <jcej@chiroptera.tragus.org>. -# Source directory was `/var/home/jcej/projects/ACE_wrappers/docs/tutorials/013'. -# -# Existing files will *not* be overwritten unless `-c' is specified. -# -# This shar contains: -# length mode name -# ------ ---------- ------------------------------------------ -# 386 -rw-rw-r-- hdr -# 89 -rw-rw-r-- bodies -# 2415 -rw-rw-r-- page01.pre -# 432 -rw-rw-r-- page02.pre -# 1426 -rw-rw-r-- page03.pre -# 1049 -rw-rw-r-- page04.pre -# 268 -rw-rw-r-- page05.pre -# 914 -rw-rw-r-- page06.pre -# 1368 -rw-rw-r-- page07.pre -# 862 -rw-rw-r-- page08.pre -# 204 -rw-rw-r-- page02.pst -# 704 -rw-rw-r-- page04.pst -# 386 -rw-rw-r-- page06.pst -# 371 -rw-rw-r-- page07.pst -# -save_IFS="${IFS}" -IFS="${IFS}:" -gettext_dir=FAILED -locale_dir=FAILED -first_param="$1" -for dir in $PATH -do - if test "$gettext_dir" = FAILED && test -f $dir/gettext \ - && ($dir/gettext --version >/dev/null 2>&1) - then - set `$dir/gettext --version 2>&1` - if test "$3" = GNU - then - gettext_dir=$dir - fi - fi - if test "$locale_dir" = FAILED && test -f $dir/shar \ - && ($dir/shar --print-text-domain-dir >/dev/null 2>&1) - then - locale_dir=`$dir/shar --print-text-domain-dir` - fi -done -IFS="$save_IFS" -if test "$locale_dir" = FAILED || test "$gettext_dir" = FAILED -then - echo=echo -else - TEXTDOMAINDIR=$locale_dir - export TEXTDOMAINDIR - TEXTDOMAIN=sharutils - export TEXTDOMAIN - echo="$gettext_dir/gettext -s" -fi -touch -am 1231235999 $$.touch >/dev/null 2>&1 -if test ! -f 1231235999 && test -f $$.touch; then - shar_touch=touch -else - shar_touch=: - echo - $echo 'WARNING: not restoring timestamps. Consider getting and' - $echo "installing GNU \`touch', distributed in GNU File Utilities..." - echo -fi -rm -f 1231235999 $$.touch -# -if mkdir _sh30349; then - $echo 'x -' 'creating lock directory' -else - $echo 'failed to create lock directory' - exit 1 -fi -# ============= hdr ============== -if test -f 'hdr' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'hdr' '(file already exists)' -else - $echo 'x -' extracting 'hdr' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'hdr' && -<HTML> -<HEAD> -X <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> -X <META NAME="Author" CONTENT="James CE Johnson"> -X <TITLE>ACE Tutorial 013</TITLE> -</HEAD> -<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F"> -X -<CENTER><B><FONT SIZE=+2>ACE Tutorial 013</FONT></B></CENTER> -X -<CENTER><B><FONT SIZE=+2>Multiple thread pools</FONT></B></CENTER> -SHAR_EOF - $shar_touch -am 1114225598 'hdr' && - chmod 0664 'hdr' || - $echo 'restore of' 'hdr' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'hdr:' 'MD5 check failed' -abef9831eba4051526151ff2343730d7 hdr -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'hdr'`" - test 386 -eq "$shar_count" || - $echo 'hdr:' 'original size' '386,' 'current size' "$shar_count!" - fi -fi -# ============= bodies ============== -if test -f 'bodies' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'bodies' '(file already exists)' -else - $echo 'x -' extracting 'bodies' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'bodies' && -PAGE=2 -message_queue.cpp -mld.h mld.cpp -block.h -block.cpp -task.h task.cpp -work.h work.cpp -SHAR_EOF - $shar_touch -am 1114230198 'bodies' && - chmod 0664 'bodies' || - $echo 'restore of' 'bodies' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'bodies:' 'MD5 check failed' -826e1e15e593f64228b867cb6143f179 bodies -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'bodies'`" - test 89 -eq "$shar_count" || - $echo 'bodies:' 'original size' '89,' 'current size' "$shar_count!" - fi -fi -# ============= page01.pre ============== -if test -f 'page01.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page01.pre' '(file already exists)' -else - $echo 'x -' extracting 'page01.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page01.pre' && -<P> -<HR WIDTH="100%"> -<P> -My intent with this tutorial was to derive from ACE_Data_Block instead -of ACE_Message_Block so that we could leverage the reference counting -nature of that object. -<P> -Along the way, I sort of got distracted... What I ended up with is a -poor excuse for ACE_Stream that implements a simple state machine. -<P> -The application is built around a thread pool where the pool's svc() -method takes work units from the message queue for processing. As -each unit is taken from the queue, the process() method is invoked to -do some work. The twist is that after processing the message, we -enqueue it into another thread pool to do more work. This continues -through a chain of thread pools until the last where the unit's fini() -method is called for finishing up any outstanding work. -<P> -The chain of thread pools is uni-directional using a singly-linked -list of Task derivatives. Each pool has the same number of tasks in -order to keep things simple. -<P> -Kirthika's abstract: -<UL> -In this tutorial, a singly linked list of thread-pools, each of which is -a subtask and which acts as the finite state machine node, is used to -simulate a finite state machine. -<P> -A task is created with a number of subtasks. Once the message block is -obtained from the queue, it is verified to see whether a task has a -subtask. If so, it is forwarded to the subtask. Thus the mesage -traverses over the whole list. As a safety measure for destroying the -block after it goes through the whole list, an effective and simple -Memory Leak Detector has been implemented. It is a counter which -increments when the object where it resides is created and decrements on -its deletion. -<P> -Another optimisation from the previous tutorials on Message Queues, is -the bundling of the Data block within the Message Block. The Data block -provides reference counting, so duplication of data is avoided. It is -deleted only when its reference count drops to zero. Now updating -this count between threads call for synchronisation and in comes the -ACE_Mutex, a lock which takes care that the counting is thread-safe. -<P> -Although the example isn't a full-fledged Finite State Machine, -i.e. it has to be tweaked to be able to jump states on different inputs, -it definitely proves to be a great lesson and introduces us to quite a -few new ACE classes and the ways they can be mixed and matched to -produce the end-system desired. -</ul> -SHAR_EOF - $shar_touch -am 0131114799 'page01.pre' && - chmod 0664 'page01.pre' || - $echo 'restore of' 'page01.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page01.pre:' 'MD5 check failed' -52884c61973afc64e96c907493ebc216 page01.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page01.pre'`" - test 2415 -eq "$shar_count" || - $echo 'page01.pre:' 'original size' '2415,' 'current size' "$shar_count!" - fi -fi -# ============= page02.pre ============== -if test -f 'page02.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page02.pre' '(file already exists)' -else - $echo 'x -' extracting 'page02.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page02.pre' && -X -X -<P> -<HR WIDTH="100%"> -<P> -We'll go back to our tradition of looking at main() first. The only -change here from our "normal" thread pool is the ability to specify -the number of subtasks for the pool. (Each subtask is another thread -pool in the chain. I suppose I should have named that better...) -I've still got the custom Message_Block so that, at this level, we -don't even know about custom Data_Blocks. -<P> -<HR WIDTH="100%"> -SHAR_EOF - $shar_touch -am 1114225598 'page02.pre' && - chmod 0664 'page02.pre' || - $echo 'restore of' 'page02.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page02.pre:' 'MD5 check failed' -6f4a2e24d7d776b1ec17a07f00f409f8 page02.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page02.pre'`" - test 432 -eq "$shar_count" || - $echo 'page02.pre:' 'original size' '432,' 'current size' "$shar_count!" - fi -fi -# ============= page03.pre ============== -if test -f 'page03.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page03.pre' '(file already exists)' -else - $echo 'x -' extracting 'page03.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page03.pre' && -X -X -<P> -<HR WIDTH="100%"> -<P> -I did eventually create that ACE_Data_Block derivative that I wanted. -My purpose in doing so was to use the reference-counting -that is provided by ACE_Data_Block and ACE_Message_Block interactions. -X When you're working with an object in a single -thread, it's generally not so difficult to manage it's lifetime. -That is, it doesn't tend to go out of scope or get destroyed unless -you do it on purpose. -<P> -On the other hand, if you're passing data between several threads, it -is easy to loose track of who "owns" the data at any one time. All -too frequently, data will be deleted by one thread while another is -still using it. Reference counting can prevent that. The rule of -thumb is that you increment the reference count of the object when you -hand it off to a new thread. You then decrement the count when you're -done with the object and let the object delete itself when there are -no more references. -<P> -To prove that all of that works correctly in the tutorial, I've -created a cheap Memory Leak Detector object. All mld instances -reference a thread-safe counter that is incremented when the mld is -constructed and decremented when destructed. I then insert an mld -into each of my dynamically created objects. If I get to the end of -main() and the counter isn't zero then I either didn't delete enough -or I deleted too many times. -<P> -Simple, cheap, effective. -<P> -<HR WIDTH="100%"> -SHAR_EOF - $shar_touch -am 1114225598 'page03.pre' && - chmod 0664 'page03.pre' || - $echo 'restore of' 'page03.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page03.pre:' 'MD5 check failed' -e4c0dfb0a761a258adeba509ac6c2062 page03.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page03.pre'`" - test 1426 -eq "$shar_count" || - $echo 'page03.pre:' 'original size' '1426,' 'current size' "$shar_count!" - fi -fi -# ============= page04.pre ============== -if test -f 'page04.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page04.pre' '(file already exists)' -else - $echo 'x -' extracting 'page04.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page04.pre' && -X -X -<P> -<HR WIDTH="100%"> -<P> -Let's look now at the changes to our ACE_Message_Block derivative and -the new ACE_Data_Block derivative. -<P> -The important thing to remember is that the data block (not the -message block) is reference counted. When you instantiate a new -ACE_Message_Block, it will create one or more ACE_Data_Block objects -to contain the data you need. Optionally, you can provide it with a -pointer to a data block. -<P> -When you finish with a message block, you should use the release() -method to make it go away. Do not ever <em>delete</em> an instance of -a message block! When you invoke release(), the message block will -invoke release() on the data block(s) it contains. If the block's -reference count goes to zero as a result then the block will <em>delete</em> -itself. -<P> -To increment the reference count of a data block, use the -duplicate() method of the message block (or blocks) to get a new -message block referencing the same data block. This is very efficient -since the actual data is not copied. -<P> -<HR WIDTH="100%"> -SHAR_EOF - $shar_touch -am 1114225598 'page04.pre' && - chmod 0664 'page04.pre' || - $echo 'restore of' 'page04.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page04.pre:' 'MD5 check failed' -05d0560194222144a3a599b4d88990ff page04.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page04.pre'`" - test 1049 -eq "$shar_count" || - $echo 'page04.pre:' 'original size' '1049,' 'current size' "$shar_count!" - fi -fi -# ============= page05.pre ============== -if test -f 'page05.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page05.pre' '(file already exists)' -else - $echo 'x -' extracting 'page05.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page05.pre' && -X -X -<P> -<HR WIDTH="100%"> -<P> -On this page we have the code for the Data_Block and Message_Block -objects. As you probably suspect from the header on the previous -page, the complicated part is in the construction and destruction of -the Data_Block. -<P> -<HR WIDTH="100%"> -SHAR_EOF - $shar_touch -am 1114225598 'page05.pre' && - chmod 0664 'page05.pre' || - $echo 'restore of' 'page05.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page05.pre:' 'MD5 check failed' -a95fdcd3db2356b091228728f4f3f130 page05.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page05.pre'`" - test 268 -eq "$shar_count" || - $echo 'page05.pre:' 'original size' '268,' 'current size' "$shar_count!" - fi -fi -# ============= page06.pre ============== -if test -f 'page06.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page06.pre' '(file already exists)' -else - $echo 'x -' extracting 'page06.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page06.pre' && -X -X -<P> -<HR WIDTH="100%"> -<P> -Let's take a look now at the new Task object. This will obviously be -different from the Tasks we've created before but I think you'll be -surprised at how relatively simple it actually is. -<P> -Remember that the goal of this tutorial was to use the reference -counting abilities of the ACE_Data_Block. The only way to show that -effectively is to have a data block passed between different threads. -A thread pool isn't really going to do that so, instead, our new Task -can be part of a chain of tasks. In that way, each Task can pass the -data on to another and satisfy our need for moving the ACE_Data_Block -around. -If we've done the reference counting correctly then none of our tasks -will be trying to work with deleted data and we won't have any memory -leaks at the end. -<P> -There's not much to the header, so I've included it and the cpp file -on this one page. -<P> -<HR WIDTH="100%"> -SHAR_EOF - $shar_touch -am 1114225698 'page06.pre' && - chmod 0664 'page06.pre' || - $echo 'restore of' 'page06.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page06.pre:' 'MD5 check failed' -a4c9b50df3240c5134733d2033fd5f03 page06.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page06.pre'`" - test 914 -eq "$shar_count" || - $echo 'page06.pre:' 'original size' '914,' 'current size' "$shar_count!" - fi -fi -# ============= page07.pre ============== -if test -f 'page07.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page07.pre' '(file already exists)' -else - $echo 'x -' extracting 'page07.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page07.pre' && -X -X -<P> -<HR WIDTH="100%"> -<P> -I've been trying to justify the chain of tasks by talking about a -Work object that implements a state machine. The idea is that your -Work object has to perform a series of discrete steps to complete it's -function. Traditionally, all of those steps would take place in one -thread of execution. That thread would probably be one from a Task -thread pool. -<P> -Suppose, however, that some of those steps spend a lot of time waiting -for disk IO. You could find that all of your thread-pool threads -are just sitting there waiting for the disk. You might then be -tempted to increase the thread pool size to get more work through. -However, if some of the stages are memory intensive, you could run out -of memory if all of the workers get to that state at the same time. -<P> -One solution might be to have different thread pools for each state. -Each pool could have it's size tuned appropriately for the work that -would be done there. That's where the chain of Tasks comes in. -X In this tutorial's implementation I've taken the -easy route and set all of the thread pools to the same size but a more -realistic solution would be to set each thread pool in the chain to a -specific size as needed by that state of operation. -<P> -There's not much to this header either so I've combined it with the -cpp file as with task. -<P> -<HR WIDTH="100%"> -SHAR_EOF - $shar_touch -am 1114225698 'page07.pre' && - chmod 0664 'page07.pre' || - $echo 'restore of' 'page07.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page07.pre:' 'MD5 check failed' -9bd5ac0cf6ff9786f3f99602a282146d page07.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page07.pre'`" - test 1368 -eq "$shar_count" || - $echo 'page07.pre:' 'original size' '1368,' 'current size' "$shar_count!" - fi -fi -# ============= page08.pre ============== -if test -f 'page08.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page08.pre' '(file already exists)' -else - $echo 'x -' extracting 'page08.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page08.pre' && -X -X -<P> -<HR WIDTH="100%"> -<P> -And that's the end of another tutorial. This one is probably the most -complicated so far because I've introduced or expanded upon -a number of different -concepts. Namely: state machines, reference counting and task -chaining. I hope I didn't complicate things to the point where the -lesson got lost in the noise. As always, feel free to drop a note to -the ACE-Users mailing list if you feel that some of this could use a -little more explaination. -X -<P> -<UL> -<LI><A HREF="Makefile">Makefile</A> -<LI><A HREF="block.cpp">block.cpp</A> -<LI><A HREF="block.h">block.h</A> -<LI><A HREF="message_queue.cpp">message_queue.cpp</A> -<LI><A HREF="mld.cpp">mld.cpp</A> -<LI><A HREF="mld.h">mld.h</A> -<LI><A HREF="task.cpp">task.cpp</A> -<LI><A HREF="task.h">task.h</A> -<LI><A HREF="work.cpp">work.cpp</A> -<LI><A HREF="work.h">work.h</A> -</UL> -<P> -SHAR_EOF - $shar_touch -am 1114231398 'page08.pre' && - chmod 0664 'page08.pre' || - $echo 'restore of' 'page08.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page08.pre:' 'MD5 check failed' -c035c8da307bddcab1d1031f5242aadc page08.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page08.pre'`" - test 862 -eq "$shar_count" || - $echo 'page08.pre:' 'original size' '862,' 'current size' "$shar_count!" - fi -fi -# ============= page02.pst ============== -if test -f 'page02.pst' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page02.pst' '(file already exists)' -else - $echo 'x -' extracting 'page02.pst' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page02.pst' && -<HR WIDTH="100%"> -<P> -Nothing really surprising here... Just remember that your total -number of threads is ( ( 1 + subtasks ) * threads ). You probably -don't want to get too carried away with that! -<P> -SHAR_EOF - $shar_touch -am 1114225798 'page02.pst' && - chmod 0664 'page02.pst' || - $echo 'restore of' 'page02.pst' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page02.pst:' 'MD5 check failed' -a8c43c5c68518f6eb8c03701d1603a92 page02.pst -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page02.pst'`" - test 204 -eq "$shar_count" || - $echo 'page02.pst:' 'original size' '204,' 'current size' "$shar_count!" - fi -fi -# ============= page04.pst ============== -if test -f 'page04.pst' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page04.pst' '(file already exists)' -else - $echo 'x -' extracting 'page04.pst' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page04.pst' && -<HR WIDTH="100%"> -<P> -One of the most difficult parts of this to get right was the Lock -object. I didn't even have it in the beginning but I soon realized -that the reference counts were getting weird. A little careful -reading of the comments and the source informed me that some sort of -locking is necessary to keep the counter sane. The simplest thing at -that point was to use the ACE_Lock_Adaptor<> to adapt ACE_Mutex -appropriately. The next trick was to ensure that the lock object was -destroyed at the proper time to prevent both memory leaks and core -dumps. The finaly product may be a little bit intimidating at first -but it's really quite simple once you understand the motivation. -<P> -SHAR_EOF - $shar_touch -am 1114225798 'page04.pst' && - chmod 0664 'page04.pst' || - $echo 'restore of' 'page04.pst' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page04.pst:' 'MD5 check failed' -325565f3f72961b842b612caeb93b36a page04.pst -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page04.pst'`" - test 704 -eq "$shar_count" || - $echo 'page04.pst:' 'original size' '704,' 'current size' "$shar_count!" - fi -fi -# ============= page06.pst ============== -if test -f 'page06.pst' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page06.pst' '(file already exists)' -else - $echo 'x -' extracting 'page06.pst' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page06.pst' && -<HR WIDTH="100%"> -<P> -So you see... it wasn't really that much more complicated. We really -just have to remember to pass to <i>next_</i> when we finish working -on the data. If your Unit_Of_Work derivative is going to implement a -state machine be sure that you also implement a fini() method -<em>or</em> ensure that your chain of subtasks is large enough for all -possible states. -<P> -SHAR_EOF - $shar_touch -am 1114225798 'page06.pst' && - chmod 0664 'page06.pst' || - $echo 'restore of' 'page06.pst' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page06.pst:' 'MD5 check failed' -fb9a3381fc937578fe01ceca882df8be page06.pst -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page06.pst'`" - test 386 -eq "$shar_count" || - $echo 'page06.pst:' 'original size' '386,' 'current size' "$shar_count!" - fi -fi -# ============= page07.pst ============== -if test -f 'page07.pst' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page07.pst' '(file already exists)' -else - $echo 'x -' extracting 'page07.pst' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page07.pst' && -<HR> -<P> -And that is that. For a more complex machine that may want to "jump -states" you would have to set some "state information" (sorry, bad -choice of terminology again) so that process() could decide what to do -at each call. You might also modify Task::svc() so that it will -respect the return value of process() and do something useful with the -information. -<P> -SHAR_EOF - $shar_touch -am 1114231398 'page07.pst' && - chmod 0664 'page07.pst' || - $echo 'restore of' 'page07.pst' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page07.pst:' 'MD5 check failed' -8d919ab7e0d5ff90e50cc785564b2f67 page07.pst -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page07.pst'`" - test 371 -eq "$shar_count" || - $echo 'page07.pst:' 'original size' '371,' 'current size' "$shar_count!" - fi -fi -rm -fr _sh30349 -exit 0 |