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temporal operator in drools,action that happened within frame of time and after another action

I have a field in object A that happened once in time and field accountActivationDate which may happen at some fixed point of time.
I want to check in drools whether A happened in period of 3 days since accountActivationDate happened.
$t: Transaction(amount > 2000, A after[3d] accountActivationDate)
This is not what i'm looking for cause if A happened 1 day after accountActivationDate then statement is false according to drools and i want it to be true until 3 days pass.
Thank you for help

Ok i found solution good enough for me it's simply:
$t: Transaction(amount > 2000, A after[1ms,3d] accountActivationDate)

Formatting time to remove unnecessary 00's from the timer

I'm trying to clean up my timer for my application but im having difficulties getting it to do what I want.
Would anyone know how to format H:M:S and remove the 00's?
Example the time may start like this: 12:34:56 (hh:mm:ss)
But once the time reaches lets say 00:34:56, remove the remaining 00's,
I'm a bit worried about performance which is why I'm here to find the more efficient way to format the time as this will be called a lot.
Would String.format("%02d:%02d", m, s).replaceAll("00:",""); be a wise choice?
Thanks.

Using a regular expression, you can delete only the first section '00:' using (It's only for deleting the hour part in a HH:MM::SS time format)
String.format("%02d:%02d", m, s).replaceAll("^00:","");
^ is a character to mark the beginning of a line

I assume you could be negligibly faster by just checking the first 2 characters:
if (timeString.charAt(0) == '0' && timeString.charAt(1) == '0')
timeString = timeString.substring(3);
I don't necessarily think that's great code, but 2 character checks would probably be faster than a larger string search. Not by much, though, so I doubt it's worth it.
(Made a fix based on the comment, changing == '1' to == '0' )

You have practically answered your own question. Just turn your thoughts into code.
What you need:
If the time is less than one hour, show only minutes and seconds; else, show hours, minutes and seconds.
Your code should read like the spoken version:
if (hours < 1) {
text = String.format("%02d:%02d", minutes, seconds);
} else {
text = String.format("%02d:%02d:%02d", hours, minutes, seconds);
}
Simple, clean, fast, and easy for future programmers (including yourself, a year from now) to understand.

How to obtain current TAI time?

How can I obtain the current TAI time in milliseconds in Linux using either Java or C++?
The reason I need this is to be able to accurately take timestamps over a long period of time (on the order of years) and still be able to compare them, without worrying about leap seconds. It is possible for multiple measurements to take place during a leap second and all measurements need to be unambiguous, monotonically increasing, and linearly increasing. This will be a dedicated Linux server. This is for a scientific project which needs precision of about .5 seconds.
I do not currently wish to invest in a GPS timekeeper and hope to use NTP to pool.ntp.org in order to keep the system clock on track.
I have looked into the following solutions:
Java 8 or the ThreeTen Project
The only way to obtain a TAIInstant is to use an Instant and then convert it which, according to the specs, "Conversion from an Instant will not be completely accurate near a leap second in accordance with UTC-SLS." That in and of itself is not a big deal (in fact, using UTC-SLS would also be acceptable). However, using now() in the Instant class also seems to just be a wrapper for System.currentTimeMillis(), which makes me think that during the leap second, the time will still be ambiguous and the project will not actually give me TAI time. The Java 8 specifications also state:
Implementations of the Java time-scale using the JSR-310 API are not
required to provide any clock that is sub-second accurate, or that
progresses monotonically or smoothly. Implementations are therefore
not required to actually perform the UTC-SLS slew or to otherwise be
aware of leap seconds.
Using a right/? timezone
This seems like it would work, however I am not sure if the implementation is smart enough to continue working during a leap second or if System.currentTimeMillis() would even give TAI time. In other words, would the underlying implementation still use UTC, thus giving an ambiguous time during the leap second which is then converted to TAI, or does using a right/ timezone actually work with TAI using System.currentTimeMillis() always (ie even during leap second)?
Using CLOCK_TAI
I tried using CLOCK_TAI in the Linux kernel but found it to be completely identical to CLOCK_REALTIME in my test:
Code:
#include <iostream>
#include <time.h>
long sec(int clock)
{
struct timespec gettime_now;
clock_gettime(clock, &gettime_now);
return gettime_now.tv_sec;
}
int main()
{
std::cout << sec(0) << std::endl; // CLOCK_REALTIME
std::cout << sec(1) << std::endl; // CLOCK_MONOTONIC
std::cout << sec(11) << std::endl; // CLOCK_TAI
return 0;
}
The output was simply:
1427744797
6896
1427744797
Using CLOCK_MONOTONIC
The problem with this is that the timestamps need to remain valid and comparable even if the computer restarts.

CLOCK_REALTIME and CLOCK_TAI return the same because the kernel parameter tai_offset is zero.
Check by using adjtimex(timex tmx) and read the value. I think that ntpd will set it if it is new enough (>4.2.6) and has a leap second file. It may also be able to get it from upstream servers but I haven't been able to verify. The call adjtimex() can set tai_offset manually when run as root. You will need a new-ish man page for adjtimex to see the parameters to set. My debian man page was too old but the command worked.

In addition to the correct accepted answer I would also mention the free Java library Time4J (min version v4.1) as possible solution because
I have written it to fill a gap in Java world (java.time cannot do all),
other answers given so far only talk about C++ (but you also asked for Java),
it works according to the same principles described by #user3427419.
It uses a monotonic clock based on System.nanoTime() but even allows custom implementations via the interface TickProvider. For the purpose of calibration, you can either use net.time4j.SystemClock.MONOTONIC, or you use an SNTP-clock named SntpConnector which just needs some simple configuration to connect to any NTP-time-server you want. And thanks to the built-in leap-second-table Time4J can even show you the announced leap second at the end of this month - in ISO-8601-notation or even as formatted local timestamp string in any timezone (using i18n-module).
A recalibration (in case of NTP - reconnect) of the clocks is possible meaning the clocks can be adapted to intermediate time adjustments (although I strongly recommend not to do it during your measurements or during a leap second). Although such a reconnect of an SNTP clock would normally cause the time stepping back in some cases Time4J tries to apply a smoothing algorithm (if activated in clock configuration) to ensure monotone behaviour. Detailed documentation is available online.
Example:
// Step 0: configure your clock
String ntpServer = "ptbtime1.ptb.de";
SntpConnector clock = new SntpConnector(ntpServer);
// Step 1: Timestamp start of the program and associate it with a counter
clock.connect();
// Step 2: Use the counter for sequential measurements at fixed intervals
Moment m = clock.currentTime();
System.out.println(m); // possible output = 2015-06-30T23:59:60,123456789Z
// Step 3: Timestamp new counter value(s) as necessary to keep your data adequately synced
clock.connect();
I doubt if any C++-based solution is more simple. More code demonstrations can also be studied on DZone.
Update (answer to question in comment):
A slightly simplified solution how to automatically download the given IETF-resource for new leap seconds and to translate it into a Time4J-specific format might look like this:
URL url = new URL("https://www.ietf.org/timezones/data/leap-seconds.list");
BufferedReader br =
new BufferedReader(
new InputStreamReader(url.openStream(), "US-ASCII"));
String line;
PlainDate expires = null;
Moment ntpEpoch = PlainTimestamp.of(1900, 1, 1, 0, 0).atUTC();
List<PlainDate> events = new ArrayList<PlainDate>();
try {
while ((line = br.readLine()) != null) {
if (line.startsWith("##")) {
long expraw = Long.parseLong(line.substring(2).trim());
expires = ntpEpoch.plus(
expraw, TimeUnit.SECONDS)
.toZonalTimestamp(ZonalOffset.UTC).toDate();
continue;
} else if (line.startsWith("#")) {
continue; // comment line
}
// this works for some foreseeable future
long epoch = Long.parseLong(line.substring(0, 10));
// this is no leap second
// but just the official introduction of modern UTC scale
if (epoch == 2272060800L) {
continue;
}
// -1 because we don't want to associate
// the leap second with the following day
PlainDate event =
ntpEpoch.plus(epoch - 1, TimeUnit.SECONDS)
.toZonalTimestamp(ZonalOffset.UTC).toDate();
events.add(event); // we don't assume any negative leap seconds here for simplicity
}
} finally {
br.close();
}
// now let's write the result into time4j-format
// use a location relative to class path of main program (see below)
String path = "C:/work/leapseconds.txt";
Writer writer = new FileWriter(new File(path));
String sep = System.getProperty("line.separator");
try {
for (PlainDate event : events) {
writer.write(event + ", +" + sep);
}
writer.write("#expires=" + expires + sep);
} finally {
writer.close();
}
System.out.println(
"Leap second file was successfully written from IETF-resource.");
// And finally, we can start the main program in a separate process
// with the system property "net.time4j.scale.leapseconds.path"
// set to our leapsecond file path (must be relative to class path)
Some notes:
I recommend to write this code as subprogram called by a simple batch program in order to avoid the main program being dependent on internet connectivity. This batch file would finally call the main program with the mentioned system property. If you set this property then the leap seconds will be read from the file specified there, and any eventually available tzdata-module would then stop to yield any concurrent leap second informations.

The reason I need this is to be able to accurately take timestamps
over a long period of time (on the order of years) and still be able
to compare them, without worrying about leap seconds. It is possible
for multiple measurements to take place during a leap second and all
measurements need to be unambiguous, monotonically increasing, and
linearly increasing.
Then your design is suboptimal. You cannot use time and then somehow meddle through leap seconds. This actually comes up often enough and people fall into the same trap of timestamping measurements using wall clock.
Timestamp start of the program and associate it with a counter
Use the counter for sequential measurements at fixed intervals
Timestamp new counter value(s) as necessary to keep your data adequately synced
If you avoid timestamping for the 1 second that leapsecond can occur (midnight!), you are home free because those can be adjusted later.
Now if you insist on using TAI without counter, all you need is a table with leap seconds that need to be accounted for. Then just use monotonic time. There is also libraries that can do this for you, but they may be out of date so you'll have to maintain them yourself,
http://skarnet.org/software/skalibs/libstddjb/tai.html

You have to implement a TAI clock based on C++ std::steady_clock or similar. To synchronize your TAI clock you could rely on GPS or NTP.
Option TAI from NTP: Your TAI implementation would need knowledge about leap seconds. Probably NTP protocol or referenced resources are the most reliable sources of current and future leap seconds.
Option TAI from GPS: GPS clock has a fixed offset to TAI, you do not have to mess with leap seconds

Why does the MongoDB Java driver use a random number generator in a conditional?

I saw the following code in this commit for MongoDB's Java Connection driver, and it appears at first to be a joke of some sort. What does the following code do?
if (!((_ok) ? true : (Math.random() > 0.1))) {
return res;
}
(EDIT: the code has been updated since posting this question)

After inspecting the history of that line, my main conclusion is that there has been some incompetent programming at work.
That line is gratuitously convoluted. The general form
a? true : b
for boolean a, b is equivalent to the simple
a || b
The surrounding negation and excessive parentheses convolute things further. Keeping in mind De Morgan's laws it is a trivial observation that this piece of code amounts to
if (!_ok && Math.random() <= 0.1)
return res;
The commit that originally introduced this logic had
if (_ok == true) {
_logger.log( Level.WARNING , "Server seen down: " + _addr, e );
} else if (Math.random() < 0.1) {
_logger.log( Level.WARNING , "Server seen down: " + _addr );
}
—another example of incompetent coding, but notice the reversed logic: here the event is logged if either _ok or in 10% of other cases, whereas the code in 2. returns 10% of the times and logs 90% of the times. So the later commit ruined not only clarity, but correctness itself.
I think in the code you have posted we can actually see how the author intended to transform the original if-then somehow literally into its negation required for the early return condition. But then he messed up and inserted an effective "double negative" by reversing the inequality sign.
Coding style issues aside, stochastic logging is quite a dubious practice all by itself, especially since the log entry does not document its own peculiar behavior. The intention is, obviously, reducing restatements of the same fact: that the server is currently down. The appropriate solution is to log only changes of the server state, and not each its observation, let alone a random selection of 10% such observations. Yes, that takes just a little bit more effort, so let's see some.
I can only hope that all this evidence of incompetence, accumulated from inspecting just three lines of code, does not speak fairly of the project as a whole, and that this piece of work will be cleaned up ASAP.

https://github.com/mongodb/mongo-java-driver/commit/d51b3648a8e1bf1a7b7886b7ceb343064c9e2225#commitcomment-3315694
11 hours ago by gareth-rees:
Presumably the idea is to log only about 1/10 of the server failures (and so avoid massively spamming the log), without incurring the cost of maintaining a counter or timer. (But surely maintaining a timer would be affordable?)

Add a class member initialized to negative 1:
private int logit = -1;
In the try block, make the test:
if( !ok && (logit = (logit + 1 ) % 10) == 0 ) { //log error
This always logs the first error, then every tenth subsequent error. Logical operators "short-circuit", so logit only gets incremented on an actual error.
If you want the first and tenth of all errors, regardless of the connection, make logit class static instead of a a member.
As had been noted this should be thread safe:
private synchronized int getLogit() {
return (logit = (logit + 1 ) % 10);
}
In the try block, make the test:
if( !ok && getLogit() == 0 ) { //log error
Note: I don't think throwing out 90% of the errors is a good idea.

I have seen this kind of thing before.
There was a piece of code that could answer certain 'questions' that came from another 'black box' piece of code. In the case it could not answer them, it would forward them to another piece of 'black box' code that was really slow.
So sometimes previously unseen new 'questions' would show up, and they would show up in a batch, like 100 of them in a row.
The programmer was happy with how the program was working, but he wanted some way of maybe improving the software in the future, if possible new questions were discovered.
So, the solution was to log unknown questions, but as it turned out, there were 1000's of different ones. The logs got too big, and there was no benefit of speeding these up, since they had no obvious answers. But every once in a while, a batch of questions would show up that could be answered.
Since the logs were getting too big, and the logging was getting in the way of logging the real important things he got to this solution:
Only log a random 5%, this will clean up the logs, whilst in the long run still showing what questions/answers could be added.
So, if an unknown event occurred, in a random amount of these cases, it would be logged.
I think this is similar to what you are seeing here.
I did not like this way of working, so I removed this piece of code, and just logged these
messages to a different file, so they were all present, but not clobbering the general logfile.

Logical Time Display in android

My android application needs to display time which has to be incremented according to a logical check
my condition example is below
d = (String) DateFormat.format("yyyy-MM-dd,hh:mm:ss", new java.util.Date());
if(condition)
{
//i want to increment the time for about an hour and display
}
else
{
// increment the date to 1 and display
}
am not concerned about the condition but on the code for incrementation of time and date
now how to code in order to increment accordingly to the above mentioned time format

Umm.
Use Calendar instead.
If you look at the documentation, you should be able to figure out how to do what you want.
If you can't figure it out from the docs (after putting forth honest effort), then I'll be happy to elaborate on the process.