From 5c94bff143dd5876046e528855497a96cd2bb55a Mon Sep 17 00:00:00 2001
From: Kai Reinhard <K.Reinhard@micromata.de>
Date: Sun, 09 Dec 2018 12:28:29 +0000
Subject: [PATCH] Caches... (compressing started).

---
 borgbutler-core/src/main/java/de/micromata/borgbutler/cache/AbstractCache.java |   82 ++++++++++++++++++++++++++++++++++++----
 1 files changed, 73 insertions(+), 9 deletions(-)

diff --git a/borgbutler-core/src/main/java/de/micromata/borgbutler/cache/AbstractCache.java b/borgbutler-core/src/main/java/de/micromata/borgbutler/cache/AbstractCache.java
index b1fc92d..569c11f 100644
--- a/borgbutler-core/src/main/java/de/micromata/borgbutler/cache/AbstractCache.java
+++ b/borgbutler-core/src/main/java/de/micromata/borgbutler/cache/AbstractCache.java
@@ -1,18 +1,20 @@
 package de.micromata.borgbutler.cache;
 
 import com.fasterxml.jackson.annotation.JsonIgnore;
-import com.fasterxml.jackson.annotation.JsonProperty;
 import de.micromata.borgbutler.config.BorgRepoConfig;
+import de.micromata.borgbutler.config.Definitions;
 import de.micromata.borgbutler.json.JsonUtils;
 import lombok.Getter;
+import org.apache.commons.compress.compressors.gzip.GzipCompressorInputStream;
+import org.apache.commons.compress.compressors.gzip.GzipCompressorOutputStream;
 import org.apache.commons.io.FileUtils;
 import org.apache.commons.io.FilenameUtils;
+import org.apache.commons.io.IOUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.io.File;
-import java.io.IOException;
-import java.nio.charset.Charset;
+import java.io.*;
+import java.util.Date;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -20,17 +22,34 @@
     private static Logger log = LoggerFactory.getLogger(AbstractCache.class);
     private static final String CACHE_FILE_PREFIX = "cache-";
     private static final String CACHE_FILE_EXTENSION = "json";
+    private static final String CACHE_FILE_ZIP_EXTENSION = ".zip";
+
+    /**
+     * INITIAL - on startup (not yet read), DIRTY - modifications not written, SAVED - content written to file.
+     */
+    private enum STATE {INITIAL, DIRTY, SAVED}
 
     @JsonIgnore
     protected File cacheFile;
+    @JsonIgnore
     @Getter
-    @JsonProperty
+    private boolean zip;
+    @JsonIgnore
+    private STATE state = STATE.INITIAL;
+    @Getter
+    private Date lastModified;
+    @Getter
+    private Date created;
+    @Getter
     protected Map<String, T> elements = new HashMap<>();
 
     public T get(BorgRepoConfig repoConfig, String identifier) {
         if (identifier == null) {
             return null;
         }
+        if (this.state == STATE.INITIAL) {
+            read();
+        }
         for (T element : elements.values()) {
             if (matches(element, identifier)) {
                 return element;
@@ -52,6 +71,7 @@
      */
     public void clear() {
         elements.clear();
+        state = STATE.DIRTY;
     }
 
     public void upsert(BorgRepoConfig repoConfig, T element) {
@@ -61,36 +81,69 @@
         } else {
             updateFrom(existingElement, element);
         }
+        state = STATE.DIRTY; // Needed to save cache to file.
     }
 
     public void read() {
         try {
             if (!cacheFile.exists()) {
                 // Cache file doesn't exist. Nothing to read.
+                state = STATE.DIRTY; // Needed to save cache to file.
                 return;
             }
             log.info("Parsing cache file '" + cacheFile.getAbsolutePath() + "'.");
-            String json = FileUtils.readFileToString(cacheFile, Charset.forName("UTF-8"));
+            String json;
+            if (zip) {
+                try (GzipCompressorInputStream in = new GzipCompressorInputStream(new FileInputStream(cacheFile))) {
+                    StringWriter writer = new StringWriter();
+                    IOUtils.copy(in, writer, Definitions.STD_CHARSET);
+                    json = writer.toString();
+                }
+            } else {
+                json = FileUtils.readFileToString(cacheFile, Definitions.STD_CHARSET);
+            }
             AbstractCache readCache = JsonUtils.fromJson(this.getClass(), json);
             if (readCache != null) {
                 this.elements = readCache.elements;
+                this.lastModified = readCache.lastModified;
+                this.created = readCache.created;
+                this.state = STATE.SAVED; // State of cache is updated from cache file.
             } else {
                 log.error("Error while parsing cache: " + cacheFile.getAbsolutePath());
+                this.state = STATE.DIRTY; // Needed to save cache to file.
             }
         } catch (IOException ex) {
             log.error("Error while trying to read cache file '" + cacheFile.getAbsolutePath() + "': "
                     + ex.getMessage(), ex);
+            this.state = STATE.DIRTY; // Needed to save cache to file.
         }
     }
 
     public void save() {
+        if (this.state == STATE.SAVED || this.state == STATE.INITIAL) {
+            log.info("Cache file is up to date (nothing to save): " + cacheFile);
+            return;
+        }
         log.info("Saving to cache file: " + cacheFile);
+        if (created == null) {
+            created = lastModified = new Date();
+        } else {
+            lastModified = new Date();
+        }
         String json = JsonUtils.toJson(this);
         try {
-            FileUtils.write(cacheFile, json, Charset.forName("UTF-8"));
+            if (this.zip) {
+                try (GzipCompressorOutputStream out = new GzipCompressorOutputStream(new FileOutputStream(cacheFile))) {
+                    IOUtils.copy(new StringReader(json), out, Definitions.STD_CHARSET);
+                }
+            } else {
+                FileUtils.write(cacheFile, json, Definitions.STD_CHARSET);
+            }
+            this.state = STATE.SAVED;
         } catch (IOException ex) {
-            log.error("Error while trying to write repos cache file '" + cacheFile.getAbsolutePath() + "': "
+            log.error("Error while trying to write cache file '" + cacheFile.getAbsolutePath() + "': "
                     + ex.getMessage(), ex);
+            this.state = STATE.DIRTY;
         }
     }
 
@@ -101,12 +154,23 @@
     }
 
     AbstractCache(File cacheDir, String cacheFilename) {
+        this(cacheDir, cacheFilename, false);
+    }
+
+    AbstractCache(File cacheDir, String cacheFilename, boolean zip) {
+        this.zip = zip;
+        String filename = CACHE_FILE_PREFIX + cacheFilename + "." + CACHE_FILE_EXTENSION;
+        if (this.zip)
+            filename = filename + CACHE_FILE_EXTENSION;
         cacheFile = new File(cacheDir, CACHE_FILE_PREFIX + cacheFilename + "." + CACHE_FILE_EXTENSION);
+        this.state = STATE.INITIAL;
     }
 
     public static boolean isCacheFile(File file) {
         String filename = file.getName();
         String extension = FilenameUtils.getExtension(filename);
-        return filename.startsWith(CACHE_FILE_PREFIX) && extension.equals(CACHE_FILE_EXTENSION);
+        return filename.startsWith(CACHE_FILE_PREFIX) &&
+                (extension.equals(CACHE_FILE_EXTENSION)
+                        || extension.equals(CACHE_FILE_EXTENSION + CACHE_FILE_ZIP_EXTENSION));
     }
 }

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