Hi Tomi. On Tue, 29 Nov 2011 14:58:00 +0200, Tomi Ollila <tomi.ollila@iki.fi> wrote: > Hi Dmitry. > > On Tue, 29 Nov 2011 01:26:39 +0400, Dmitry Kurochkin <dmitry.kurochkin@gmail.com> wrote: > > Hi Tomi. > > > > On Mon, 28 Nov 2011 22:42:50 +0200, Tomi Ollila <tomi.ollila@iki.fi> wrote: > > > On Mon, 28 Nov 2011 07:28:13 +0400, Dmitry Kurochkin <dmitry.kurochkin@gmail.com> wrote: > [ ... ] > > > > +# Creates a script that counts how much time it is executed and calls > > > > +# notmuch. $notmuch_counter_command is set to the path to the > > > > +# generated script. Use notmuch_counter_value() function to get the > > > > +# current counter value. > > > > +notmuch_counter_reset () { > > > > + notmuch_counter_command="$TMP_DIRECTORY/notmuch_counter" > > > > + if [ ! -x "$notmuch_counter_command" ]; then > > > > + notmuch_counter_state_path="$TMP_DIRECTORY/notmuch_counter.state" > > > > + cat >"$notmuch_counter_command" <<EOF || return > > > > +#!/bin/sh > > > > + > > > > +count=\$(cat "$notmuch_counter_state_path") > > > > +echo -n \$(expr \$count + 1) > "$notmuch_counter_state_path" > > > > + > > > > +exec notmuch "\$@" > > > > +EOF > > > > + chmod +x "$notmuch_counter_command" || return > > > > + fi > > > > + > > > > + echo -n 0 > "$notmuch_counter_state_path" > > > > +} > > > > + > > > > +# Returns the current notmuch counter value. > > > > +notmuch_counter_value () { > > > > + if [ -r "$notmuch_counter_state_path" ]; then > > > > + count=$(cat "$notmuch_counter_state_path") > > > > + else > > > > + count=0 > > > > + fi > > > > + echo -n $count > > > > +} > > > > + > > > > > > Good work! It would be nice if the state file contained newline after > > > count number. > > > > I wonder why it is actually nice :) I do not have strong preference > > here. So a newline is added in v3. Also a newline is added to > > notmuch_counter_value() output for consistency. > > It is nice when I enter cat /path/to/notmuch_counter from command > line and shell prompt is not appended at the end of the file contents > (but on next line :) > > > > > > Also some optimizations could be done: > > > > > > > (Would be nice if you send a diff, or a human-friendly description of > > the changes.) > > Ok, I'll try to do this according to your wishes next time. > > > > cat >"$notmuch_counter_command" <<EOF || return > > > #!/bin/sh > > > > > > read count < "$notmuch_counter_state_path" > > > > Nice. Fixed in the new patch version. > > > > > echo \$((count + 1)) > "$notmuch_counter_state_path" > > > > > > > I do not think this is really an optimization. And I find expr more > > clear than using $(()). I always have troubles remembering "random > > special char syntax" (yeah, not a Perl fan :)), prefer human friendly > > words. > > The (posix) shell command language defines 'Arithmetic Expansion' in > > http://pubs.opengroup.org/onlinepubs/007908799/xcu/chap2.html#tag_001_006_004 > > I.e. using format $(( expression )) makes shell doing the arithetic itself > instead of forking a process (or two!) to do so. > I though expr was a builtin. Now I agree that it is better to replace it with $(()), even though I still prefer the expr syntax. > Normally in this case it is not so big deal (and still it isn't, but...) > In this particular case the shell wrapper counting notmuch launches and > exec'ing it the wrapper could do this without fork(2)ing a single time > (i.e. keep the process count unchanged compared to execing notmuch > directly) > > Anyway, many opinions; as far as it works I'm fine with it :) > > Now that you feel relaxed, check the results of some further > experimentation ;) : > > excerpt from man strace: > > -ff If the -o filename option is in effect, each processes > trace is written to filename.pid where pid is the > numeric process id of each process. > > Executing rm -f forked.*; strace -ff -o forked bash -c 'echo $(( 5 + 5 ))' > > will output '10' and create just one 'forked.<pid>' file > > Executing rm -f forked.*; strace -ff -o forked bash -c 'echo $(expr 5 + 5)' > > output 10 as expected, but there is now *3* forked.<pid> files ! > > bash does not optmize; it forks subshell to execute $(...) and then > there just works as usual (forks subshell to execute builtin expr)) > > Executing rm -f forked.*; strace -ff -o forked bash -c 'echo $(exec expr 5 + 5)' > > (the added 'exec' takes off one fork -- just 2 forked.<pid> files appear). > > I did the same tests using dash, ksh & zsh on linux system, and every one > of these managed to optimize one fork out in the above 3 fork case. > Thanks for details. Regards, Dmitry > > Tomi