connectors/file/src/main/java/org/apache/edgent/connectors/file/FileWriterCycleConfig.java

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to you under the Apache License, Version 2.0 (the
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  http://www.apache.org/licenses/LICENSE-2.0

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*/
package org.apache.edgent.connectors.file;

import org.apache.edgent.function.Predicate;

/**
 * FileWriter active file cycle configuration control.
 * <p>
 * Cycling the active file closes it, gets it to its final pathname,
 * and induces the application of a retention policy
 * {@link FileWriterRetentionConfig}.
 * <p>
 * Cycling the active file can be any combination of:
 * <ul>
 * <li>after {@code fileSize} bytes have been written</li>
 * <li>after every {@code cntTuple} tuples written</li>
 * <li>after {@code tuplePredicate} returns true</li>
 * <li>after {@code periodMsec} has elapsed since the last time based cycle</li>
 * </ul>
 * 
 * @param <T> stream tuple type
 */
public class FileWriterCycleConfig<T> {
    private long fileSize;
    private int cntTuples;
    private long periodMsec;
    private Predicate<T> tuplePredicate;
    
    /** same as {@code newConfig(fileSize, 0, 0, null)}
     * 
     * @param <T> Tuple type
     * @param fileSize cycle after {@code fileSize} bytes have been written. 0 to disable.
     * @return the cycle configuration
     */
    public static <T> FileWriterCycleConfig<T> newFileSizeBasedConfig(long fileSize) {
        if (fileSize < 1)
            throw new IllegalArgumentException("fileSize");
        return newConfig(fileSize, 0, 0, null);
    }
    /** same as {@code newConfig(0, cntTuples, 0, null)}
     * 
     * @param <T> Tuple type
     * @param cntTuples cycle after every {@code cntTuple} tuples have been written. 0 to disable.
     * @return the cycle configuration
     */
    public static <T> FileWriterCycleConfig<T> newCountBasedConfig(int cntTuples) {
        if (cntTuples < 1)
            throw new IllegalArgumentException("cntTuples");
        return newConfig(0, cntTuples, 0, null);
    }
    /** same as {@code newConfig(0, 0, periodMsec, null)}
     * 
     * @param <T> Tuple type
     * @param periodMsec cycle after {@code periodMsec} has elapsed since the last time based cycle. 0 to disable.
     * @return the cycle configuration
     */
    public static <T> FileWriterCycleConfig<T> newTimeBasedConfig(long periodMsec) {
        if (periodMsec < 1)
            throw new IllegalArgumentException("periodMsec");
        return newConfig(0, 0, periodMsec, null);
    }
    /** same as {@code newConfig(0, 0, 0, tuplePredicate)}
     * 
     * @param <T> Tuple type
     * @param tuplePredicate cycle if {@code tuplePredicate} returns true. null to disable.
     * @return the cycle configuration
     */
    public static <T> FileWriterCycleConfig<T> newPredicateBasedConfig(Predicate<T> tuplePredicate) {
        return newConfig(0, 0, 0, tuplePredicate);
    }
    
    /**
     * Create a new configuration.
     * <p>
     * At least one configuration mode must be enabled.
     * @param <T> Tuple type
     * @param fileSize cycle after {@code fileSize} bytes have been written. 0 to disable.
     * @param cntTuples cycle after every {@code cntTuple} tuples have been written. 0 to disable.
     * @param periodMsec cycle after {@code periodMsec} has elapsed since the last time based cycle. 0 to disable.
     * @param tuplePredicate cycle if {@code tuplePredicate} returns true. null to disable.
     * @return the cycle configuration
     */
    public static <T> FileWriterCycleConfig<T> newConfig(long fileSize, int cntTuples, long periodMsec, Predicate<T> tuplePredicate) {
        return new FileWriterCycleConfig<>(fileSize, cntTuples, periodMsec, tuplePredicate);
    }

    private FileWriterCycleConfig(long fileSize, int cntTuples, long periodMsec, Predicate<T> tuplePredicate) {
        if (fileSize < 0)
            throw new IllegalArgumentException("fileSize");
        if (cntTuples < 0)
            throw new IllegalArgumentException("cntTuples");
        if (periodMsec < 0)
            throw new IllegalArgumentException("periodMsec");
        if (fileSize==0 && cntTuples==0 && periodMsec==0 && tuplePredicate==null)
            throw new IllegalArgumentException("no cycle configuration specified");
            
        this.fileSize = fileSize;
        this.cntTuples = cntTuples;
        this.periodMsec = periodMsec;
        this.tuplePredicate = tuplePredicate;
    }
    
    /**
     * Get the file size configuration value.
     * @return the value
     */
    public long getFileSize() { return fileSize; }
    
    /**
     * Get the tuple count configuration value.
     * @return the value
     */
    public int getCntTuples() { return cntTuples; }
    
    /**
     * Get the time period configuration value.
     * @return the value
     */
    public long getPeriodMsec() { return periodMsec; }
    
    /**
     * Get the tuple predicate configuration value.
     * @return the value
     */
    public Predicate<T> getTuplePredicate() { return tuplePredicate; }
    
    /**
     * Evaluate if the specified values indicate that a cycling of
     * the active file should be performed.
     * @param fileSize the number of bytes written to the active file
     * @param nTuples number of tuples written to the active file
     * @param tuple the tuple written to the file
     * @return true if a cycle action should be performed.
     */
    public boolean evaluate(long fileSize, int nTuples, T tuple) {
        return (this.fileSize > 0 && fileSize > this.fileSize)
                || (cntTuples > 0 && nTuples > 0 && nTuples % cntTuples == 0)
                || (tuplePredicate != null && tuplePredicate.test(tuple));
    }
    
    @Override
    public String toString() {
        return String.format("fileSize:%d cntTuples:%d periodMsec:%d tuplePredicate:%s",
                getFileSize(), getCntTuples(), getPeriodMsec(),
                getTuplePredicate() == null ? "no" : "yes");
    }
}