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// demonstration file for the epoll() linux specific call, by Micha
// Nelissen
program epoll_pipe;
{$mode objfpc}{$h+}
uses
baseunix, unix, linux;
const
NumPipes = 100;
NumActive = 1;
NumWrites = NumPipes;
NumRuns = 16;
var
gPipes: array of tfildes;
gEvents: array of epoll_event;
gCount, gFired, gWrites: integer;
epoll_fd: integer;
function getustime: qword;
var
tm: timeval;
begin
fpgettimeofday(@tm, nil);
result := tm.tv_sec * 1000000 + tm.tv_usec;
end;
procedure read_cb(fd, idx: integer);
var
widx: integer;
ch: char;
begin
widx := idx + NumActive + 1;
if fpread(fd, ch, sizeof(ch)) <> 0 then
inc(gCount)
else
writeln('false read event: fd=', fd, ' idx=', idx);
if gWrites <> 0 then
begin
if widx >= NumPipes then
dec(widx, NumPipes);
fpwrite(gPipes[widx][1], 'e', 1);
dec(gWrites);
inc(gFired);
end;
end;
procedure run_once(var work: integer; var tr: qword);
var
i, res: integer;
ts, te: qword;
begin
gFired := 0;
for i := 0 to NumActive-1 do
begin
fpwrite(gPipes[i][1], 'e', 1);
inc(gFired);
end;
gCount := 0;
gWrites := NumWrites;
ts := getustime;
repeat
res := epoll_wait(epoll_fd, @gEvents[0], NumPipes, 0);
for i := 0 to res-1 do
read_cb(gPipes[gEvents[i].data.u32][0], gEvents[i].data.u32);
until gCount = gFired;
te := getustime;
tr := te-ts;
work := gCount;
end;
var
lEvent: epoll_event;
i, work: integer;
tr: qword;
begin
SetLength(gEvents, NumPipes);
SetLength(gPipes, NumPipes);
epoll_fd := epoll_create(NumPipes);
if epoll_fd = -1 then
begin
writeln('error calling epoll_create');
halt(1);
end;
for i := 0 to NumPipes-1 do
begin
if fppipe(gPipes[i]) = -1 then
begin
writeln('error calling pipe');
halt(1);
end;
fpfcntl(gPipes[i][0], F_SETFL, fpfcntl(gPipes[i][0], F_GETFL) or O_NONBLOCK);
lEvent.events := EPOLLIN;
lEvent.data.u32 := i;
if epoll_ctl(epoll_fd, EPOLL_CTL_ADD, gPipes[i][0], @lEvent) < 0 then
begin
writeln('error calling epoll_ctl');
halt(1);
end;
end;
for i := 0 to NumRuns-1 do
begin
run_once(work, tr);
if work = 0.0 then
halt(1);
writeln(double(tr)/double(work):10:7);
end;
end.
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