/*

 * Copyright (c) 2012, 2018, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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

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package jdk.jfr.internal;

import java.io.IOException;

import java.nio.file.Path;

import java.time.Instant;

import java.time.LocalDateTime;

import java.time.format.DateTimeFormatter;

import java.util.HashSet;

import java.util.Set;

import jdk.jfr.internal.SecuritySupport.SafePath;

public final class Repository {

    private static final int MAX_REPO_CREATION_RETRIES = 1000;

    private static final JVM jvm = JVM.getJVM();

    private static final Repository instance = new Repository();

            .ofPattern("yyyy_MM_dd_HH_mm_ss");

    private final Set<SafePath> cleanupDirectories = new HashSet<>();

    private SafePath baseLocation;

    private SafePath repository;

    private Repository() {

    }

    public static Repository getRepository() {

        return instance;

    }

    public synchronized void setBasePath(SafePath baseLocation) throws Exception {

        // Probe to see if repository can be created, needed for fail fast

        // during JVM startup or JFR.configure

        this.repository = createRepository(baseLocation);

        try {

            // Remove so we don't "leak" repositories, if JFR is never started

            // and shutdown hook not added.

            SecuritySupport.delete(repository);

        } catch (IOException ioe) {

            Logger.log(LogTag.JFR, LogLevel.INFO, "Could not delete disk repository " + repository);

        }

        this.baseLocation = baseLocation;

    }

    synchronized void ensureRepository() throws Exception {

        if (baseLocation == null) {

            setBasePath(SecuritySupport.JAVA_IO_TMPDIR);

        }

    }

    synchronized RepositoryChunk newChunk(Instant timestamp) {

        try {

            if (!SecuritySupport.existDirectory(repository)) {

                this.repository = createRepository(baseLocation);

                jvm.setRepositoryLocation(repository.toString());

                cleanupDirectories.add(repository);

            }

            return new RepositoryChunk(repository, timestamp);

        } catch (Exception e) {

            String errorMsg = String.format("Could not create chunk in repository %s, %s", repository, e.getMessage());

            Logger.log(LogTag.JFR, LogLevel.ERROR, errorMsg);

            jvm.abort(errorMsg);

            throw new InternalError("Could not abort after JFR disk creation error");

        }

    }

    private static SafePath createRepository(SafePath basePath) throws Exception {

        SafePath canonicalBaseRepositoryPath = createRealBasePath(basePath);

        SafePath f = null;

        String basename = REPO_DATE_FORMAT.format(LocalDateTime.now()) + "_" + JVM.getJVM().getPid();

        String name = basename;

        int i = 0;

        for (; i < MAX_REPO_CREATION_RETRIES; i++) {

            f = new SafePath(canonicalBaseRepositoryPath.toPath().resolve(name));

            if (tryToUseAsRepository(f)) {

                break;

            }

            name = basename + "_" + i;

        }

        if (i == MAX_REPO_CREATION_RETRIES) {

            throw new Exception("Unable to create JFR repository directory using base location (" + basePath + ")");

        }

        SafePath canonicalRepositoryPath = SecuritySupport.toRealPath(f);

        return canonicalRepositoryPath;

    }

    private static SafePath createRealBasePath(SafePath safePath) throws Exception {

        if (SecuritySupport.exists(safePath)) {

            if (!SecuritySupport.isWritable(safePath)) {

                throw new IOException("JFR repository directory (" + safePath.toString() + ") exists, but isn't writable");

            }

            return SecuritySupport.toRealPath(safePath);

        }

        SafePath p = SecuritySupport.createDirectories(safePath);

        return SecuritySupport.toRealPath(p);

    }

    private static boolean tryToUseAsRepository(final SafePath path) {

        Path parent = path.toPath().getParent();

        if (parent == null) {

            return false;

        }

        try {

            try {

                SecuritySupport.createDirectories(path);

            } catch (Exception e) {

                // file already existed or some other problem occurred

            }

            if (!SecuritySupport.exists(path)) {

                return false;

            }

            if (!SecuritySupport.isDirectory(path)) {

                return false;

            }

            return true;

        } catch (IOException io) {

            return false;

        }

    }

    synchronized void clear() {

        for (SafePath p : cleanupDirectories) {

            try {

                SecuritySupport.clearDirectory(p);

                Logger.log(LogTag.JFR, LogLevel.INFO, "Removed repository " + p);

            } catch (IOException e) {

                Logger.log(LogTag.JFR, LogLevel.ERROR, "Repository " + p + " could not be removed at shutdown: " + e.getMessage());

            }

        }

    }

    public synchronized SafePath getRepositoryPath() {

        return repository;

    }

}