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Resolves checkstyle errors for template-method thread-pool throttling tls tolerant-reader (#1073)

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* Reduces checkstyle errors in template-method

* Reduces checkstyle errors in thread-pool

* Reduces checkstyle errors in throttling

* Reduces checkstyle errors in tls

* Reduces checkstyle errors in tolerant-reader
This commit is contained in:
Anurag Agarwal
2019-11-10 23:15:17 +05:30
committed by Ilkka Seppälä
parent 9c8ad4485b
commit b92eb5229d
23 changed files with 176 additions and 223 deletions
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87
tls/src/main/java/com/iluwatar/tls/App.java
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@@ -23,58 +23,52 @@
package com.iluwatar.tls;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Calendar;
import java.util.Date;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* ThreadLocal pattern
* <p>
* This App shows how to create an isolated space per each thread. In this
* example the usage of SimpleDateFormat is made to be thread-safe. This is an
* example of the ThreadLocal pattern.
* <p>
* By applying the ThreadLocal pattern you can keep track of application
* instances or locale settings throughout the handling of a request. The
* ThreadLocal class works like a static variable, with the exception that it is
* only bound to the current thread! This allows us to use static variables in a
* thread-safe way.
* <p>
* In Java, thread-local variables are implemented by the ThreadLocal class
* object. ThreadLocal holds a variable of type T, which is accessible via get/set
* methods.
* <p>
* SimpleDateFormat is one of the basic Java classes and is not thread-safe. If
* you do not isolate the instance of SimpleDateFormat per each thread then
* problems arise.
* <p>
* App converts the String date value 15/12/2015 to the Date format using the
* Java class SimpleDateFormat. It does this 20 times using 4 threads, each doing
* it 5 times. With the usage of as ThreadLocal in DateFormatCallable everything
* runs well. But if you comment out the ThreadLocal variant (marked with "//TLTL")
* and comment in the non ThreadLocal variant (marked with "//NTLNTL") you can
* see what will happen without the ThreadLocal. Most likely you will get incorrect
* date values and / or exceptions.
* <p>
* This example clearly show what will happen when using non thread-safe classes
* in a thread. In real life this may happen one in of 1.000 or 10.000 conversions
* and those are really hard to find errors.
*
* @author Thomas Bauer, 2017
*
* <p>This App shows how to create an isolated space per each thread. In this example the usage of
* SimpleDateFormat is made to be thread-safe. This is an example of the ThreadLocal pattern.
*
* <p>By applying the ThreadLocal pattern you can keep track of application instances or locale
* settings throughout the handling of a request. The ThreadLocal class works like a static
* variable, with the exception that it is only bound to the current thread! This allows us to use
* static variables in a thread-safe way.
*
* <p>In Java, thread-local variables are implemented by the ThreadLocal class object. ThreadLocal
* holds a variable of type T, which is accessible via get/set methods.
*
* <p>SimpleDateFormat is one of the basic Java classes and is not thread-safe. If you do not
* isolate the instance of SimpleDateFormat per each thread then problems arise.
*
* <p>App converts the String date value 15/12/2015 to the Date format using the Java class
* SimpleDateFormat. It does this 20 times using 4 threads, each doing it 5 times. With the usage of
* as ThreadLocal in DateFormatCallable everything runs well. But if you comment out the ThreadLocal
* variant (marked with "//TLTL") and comment in the non ThreadLocal variant (marked with
* "//NTLNTL") you can see what will happen without the ThreadLocal. Most likely you will get
* incorrect date values and / or exceptions.
*
* <p>This example clearly show what will happen when using non thread-safe classes in a thread. In
* real life this may happen one in of 1.000 or 10.000 conversions and those are really hard to find
* errors.
*
* @author Thomas Bauer, 2017
*/
public class App {
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
/**
* Program entry point
*
* @param args
* command line args
* Program entry point.
*
* @param args command line args
*/
public static void main(String[] args) {
int counterDateValues = 0;
@@ -115,9 +109,9 @@ public class App {
}
/**
* Print result (date values) of a thread execution and count dates
*
* @param res contains results of a thread execution
* Print result (date values) of a thread execution and count dates.
*
* @param res contains results of a thread execution
*/
private static int printAndCountDates(Result res) {
// a correct run should deliver 5 times 15.12.2015 per each thread
@@ -128,15 +122,16 @@ public class App {
cal.setTime(dt);
// Formatted output of the date value: DD.MM.YYYY
LOGGER.info(
cal.get(Calendar.DAY_OF_MONTH) + "." + cal.get(Calendar.MONTH) + "." + +cal.get(Calendar.YEAR));
cal.get(Calendar.DAY_OF_MONTH) + "." + cal.get(Calendar.MONTH) + "." + +cal
.get(Calendar.YEAR));
}
return counter;
}
/**
* Print result (exceptions) of a thread execution and count exceptions
*
* @param res contains results of a thread execution
* Print result (exceptions) of a thread execution and count exceptions.
*
* @param res contains results of a thread execution
* @return number of dates
*/
private static int printAndCountExceptions(Result res) {

41
tls/src/main/java/com/iluwatar/tls/DateFormatCallable.java
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@@ -23,25 +23,23 @@
package com.iluwatar.tls;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.concurrent.Callable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* DateFormatCallable converts string dates to a date format using
* SimpleDateFormat. The date format and the date value will be passed to the
* Callable by the constructor. The constructor creates a instance of
* SimpleDateFormat and stores it in a ThreadLocal class variable. For the
* complete description of the example see {@link App}
*
* You can comment out the code marked with //TLTL and comment in the
* code marked //NTLNTL. Then you can see what will happen if you do not
* use the ThreadLocal. For details see the description of {@link App}
* DateFormatCallable converts string dates to a date format using SimpleDateFormat. The date format
* and the date value will be passed to the Callable by the constructor. The constructor creates a
* instance of SimpleDateFormat and stores it in a ThreadLocal class variable. For the complete
* description of the example see {@link App}.
*
* @author Thomas Bauer, 2017
* <p>You can comment out the code marked with //TLTL and comment in the code marked //NTLNTL. Then
* you can see what will happen if you do not use the ThreadLocal. For details see the description
* of {@link App}
*
* @author Thomas Bauer, 2017
*/
public class DateFormatCallable implements Callable<Result> {
@@ -51,15 +49,13 @@ public class DateFormatCallable implements Callable<Result> {
// private DateFormat df; //NTLNTL
private String dateValue; // for dateValue Thread Local not needed
/**
* The date format and the date value are passed to the constructor
*
* @param inDateFormat
* string date format string, e.g. "dd/MM/yyyy"
* @param inDateValue
* string date value, e.g. "21/06/2016"
* The date format and the date value are passed to the constructor.
*
* @param inDateFormat string date format string, e.g. "dd/MM/yyyy"
* @param inDateValue string date value, e.g. "21/06/2016"
*/
public DateFormatCallable(String inDateFormat, String inDateValue) {
final String idf = inDateFormat; //TLTL
@@ -73,9 +69,6 @@ public class DateFormatCallable implements Callable<Result> {
this.dateValue = inDateValue;
}
/**
* @see java.util.concurrent.Callable#call()
*/
@Override
public Result call() {
LOGGER.info(Thread.currentThread() + " started executing...");
@@ -88,7 +81,7 @@ public class DateFormatCallable implements Callable<Result> {
// instance of SimpleDateFormat locally
// Create the date value and store it in dateList
result.getDateList().add(this.df.get().parse(this.dateValue)); //TLTL
// result.getDateList().add(this.df.parse(this.dateValue)); //NTLNTL
// result.getDateList().add(this.df.parse(this.dateValue)); //NTLNTL
} catch (Exception e) {
// write the Exception to a list and continue work
result.getExceptionList().add(e.getClass() + ": " + e.getMessage());

14
tls/src/main/java/com/iluwatar/tls/Result.java
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@@ -32,10 +32,10 @@ import java.util.Date;
import java.util.List;
/**
* Result object that will be returned by the Callable {@link DateFormatCallable}
* used in {@link App}
* Result object that will be returned by the Callable {@link DateFormatCallable} used in {@link
* App}.
*
* @author Thomas Bauer, 2017
* @author Thomas Bauer, 2017
*/
public class Result {
// A list to collect the date values created in one thread
@@ -44,9 +44,10 @@ public class Result {
// A list to collect Exceptions thrown in one threads (should be none in
// this example)
private List<String> exceptionList = new ArrayList<String>();
/**
*
* Get list of date values collected within a thread execution.
*
* @return List of date values collected within an thread execution
*/
public List<Date> getDateList() {
@@ -54,7 +55,8 @@ public class Result {
}
/**
*
* Get list of exceptions thrown within a thread execution.
*
* @return List of exceptions thrown within an thread execution
*/
public List<String> getExceptionList() {