/*
 * Copyright (c) 2012, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.graal.api.meta;

/**
 * Provides access to the profiling information of one specific method. Every accessor method
 * returns the information that is available at the time of invocation. If a method is invoked
 * multiple times, it may return significantly different results for every invocation as the
 * profiling information may be changed by other Java threads at any time.
 */
public interface ProfilingInfo {

    /**
     * Represents the three possibilities that an exception was seen at a specific BCI.
     */
    public enum TriState {
        TRUE,
        FALSE,
        UNKNOWN;

        public static TriState get(boolean value) {
            return value ? TRUE : FALSE;
        }
    }

    /**
     * Returns the length of the bytecodes associated with this profile.
     */
    int getCodeSize();

    /**
     * Returns an estimate of how often the branch at the given byte code was taken.
     * 
     * @return The estimated probability, with 0.0 meaning never and 1.0 meaning always, or -1 if
     *         this information is not available.
     */
    double getBranchTakenProbability(int bci);

    /**
     * Returns an estimate of how often the switch cases are taken at the given BCI. The default
     * case is stored as the last entry.
     * 
     * @return A double value that contains the estimated probabilities, with 0.0 meaning never and
     *         1.0 meaning always, or -1 if this information is not available.
     */
    double[] getSwitchProbabilities(int bci);

    /**
     * Returns the TypeProfile for the given BCI.
     * 
     * @return Returns a JavaTypeProfile object, or null if not available.
     */
    JavaTypeProfile getTypeProfile(int bci);

    /**
     * Returns the MethodProfile for the given BCI.
     * 
     * @return Returns a JavaMethodProfile object, or null if not available.
     */
    JavaMethodProfile getMethodProfile(int bci);

    /**
     * Returns information if the given BCI did ever throw an exception.
     * 
     * @return {@link TriState#TRUE} if the instruction has thrown an exception at least once,
     *         {@link TriState#FALSE} if it never threw an exception, and {@link TriState#UNKNOWN}
     *         if this information was not recorded.
     */
    TriState getExceptionSeen(int bci);

    /**
     * Returns information if null was ever seen for the given BCI. This information is collected
     * for the aastore, checkcast and instanceof bytecodes.
     * 
     * @return {@link TriState#TRUE} if null was seen for the instruction, {@link TriState#FALSE} if
     *         null was NOT seen, and {@link TriState#UNKNOWN} if this information was not recorded.
     */
    TriState getNullSeen(int bci);

    /**
     * Returns an estimate how often the current BCI was executed. Avoid comparing execution counts
     * to each other, as the returned value highly depends on the time of invocation.
     * 
     * @return the estimated execution count or -1 if not available.
     */
    int getExecutionCount(int bci);

    /**
     * Returns how frequently a method was deoptimized for the given deoptimization reason. This
     * only indicates how often the method did fall back to the interpreter for the execution and
     * does not indicate how often it was recompiled.
     * 
     * @param reason the reason for which the number of deoptimizations should be queried
     * @return the number of times the compiled method deoptimized for the given reason.
     */
    int getDeoptimizationCount(DeoptimizationReason reason);

    /**
     * Records the size of the compiler intermediate representation (IR) associated with this
     * method.
     * 
     * @param irType the IR type for which the size is being recorded
     * @param irSize the IR size to be recorded. The unit depends on the IR.
     * @return whether recording this information for {@code irType} is supported
     */
    boolean setCompilerIRSize(Class<?> irType, int irSize);

    /**
     * Gets the size of the compiler intermediate representation (IR) associated with this method
     * last recorded by {@link #setCompilerIRSize(Class, int)}.
     * 
     * @param irType the IR type for which the size is being requested
     * @return the requested IR size or -1 if it is unavailable for {@code irType}
     */
    int getCompilerIRSize(Class<?> irType);

    /**
     * Returns true if the profiling information can be assumed as sufficiently accurate.
     * 
     * @return true if the profiling information was recorded often enough mature enough, false
     *         otherwise.
     */
    boolean isMature();

    /**
     * Force data to be treated as mature if possible.
     */
    void setMature();
}