Make Metadata store account for IOExceptions

rcloud-gist-service/src/main/java/com/mangosolutions/rcloud/rawgist/model/GistCommentResponse.java

@@ -118,4 +118,65 @@ public void addAdditionalProperties(Map<String, Object> properties) {
 		this.additionalProperties.putAll(properties);
 	}
 
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		result = prime * result + ((additionalProperties == null) ? 0 : additionalProperties.hashCode());
+		result = prime * result + ((body == null) ? 0 : body.hashCode());
+		result = prime * result + ((createdAt == null) ? 0 : createdAt.hashCode());
+		result = prime * result + ((id == null) ? 0 : id.hashCode());
+		result = prime * result + ((updatedAt == null) ? 0 : updatedAt.hashCode());
+		result = prime * result + ((url == null) ? 0 : url.hashCode());
+		result = prime * result + ((user == null) ? 0 : user.hashCode());
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		GistCommentResponse other = (GistCommentResponse) obj;
+		if (additionalProperties == null) {
+			if (other.additionalProperties != null)
+				return false;
+		} else if (!additionalProperties.equals(other.additionalProperties))
+			return false;
+		if (body == null) {
+			if (other.body != null)
+				return false;
+		} else if (!body.equals(other.body))
+			return false;
+		if (createdAt == null) {
+			if (other.createdAt != null)
+				return false;
+		} else if (!createdAt.equals(other.createdAt))
+			return false;
+		if (id == null) {
+			if (other.id != null)
+				return false;
+		} else if (!id.equals(other.id))
+			return false;
+		if (updatedAt == null) {
+			if (other.updatedAt != null)
+				return false;
+		} else if (!updatedAt.equals(other.updatedAt))
+			return false;
+		if (url == null) {
+			if (other.url != null)
+				return false;
+		} else if (!url.equals(other.url))
+			return false;
+		if (user == null) {
+			if (other.user != null)
+				return false;
+		} else if (!user.equals(other.user))
+			return false;
+		return true;
+	}
+
 }

rcloud-gist-service/src/main/java/com/mangosolutions/rcloud/rawgist/repository/git/GistCommentStore.java

@@ -8,18 +8,22 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.StandardCopyOption;
 import java.util.ArrayList;
 import java.util.List;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.cache.annotation.CachePut;
 import org.springframework.cache.annotation.Cacheable;
 import org.springframework.stereotype.Component;
 
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.base.Preconditions;
 import com.mangosolutions.rcloud.rawgist.model.GistCommentResponse;
 import com.mangosolutions.rcloud.rawgist.repository.GistError;
 import com.mangosolutions.rcloud.rawgist.repository.GistErrorCode;
@@ -33,6 +37,9 @@ public class GistCommentStore implements CommentStore {
 	@Autowired
 	private ObjectMapper objectMapper;
 
+	@Value("${gists.commentstore.workingCopySuffix:.tmp}")
+	private String workingCopySuffix = ".tmp";
+
 	public GistCommentStore() {
 		this.objectMapper = new ObjectMapper();
 	}
@@ -54,7 +61,8 @@ public void setObjectMapper(ObjectMapper objectMapper) {
 	@Cacheable(value = "commentstore", key = "#store.getAbsolutePath()")
 	public List<GistCommentResponse> load(File store) {
 		List<GistCommentResponse> comments = new ArrayList<>();
-		if (store.exists()) {
+		File workingCopy = workingCopyFor(store);
+		if (store.exists() || restoreState(workingCopy, store)) {
 			try {
 				comments = objectMapper.readValue(store, new TypeReference<List<GistCommentResponse>>() {
 				});
@@ -72,7 +80,15 @@ public List<GistCommentResponse> load(File store) {
 	public List<GistCommentResponse> save(File store, List<GistCommentResponse> comments) {
 		if(comments != null) {
 			try {
-				objectMapper.writeValue(store, comments);
+				File workingCopy = new File(store.getParent(), store.getName() + workingCopySuffix);
+				if(!store.exists()) {
+					restoreState(workingCopy, store);
+				}
+				write(workingCopy, comments);
+				if(store.exists()) {
+					Files.delete(store.toPath());
+				}
+				Files.move(workingCopy.toPath(), store.toPath(), StandardCopyOption.ATOMIC_MOVE);
 			} catch (IOException e) {
 				GistError error = new GistError(GistErrorCode.ERR_COMMENTS_NOT_WRITEABLE, "Could not save comments");
 				logger.error(error.getFormattedMessage() + " with path {}", store);
@@ -82,6 +98,46 @@ public List<GistCommentResponse> save(File store, List<GistCommentResponse> comm
 		return comments;
 	}
 
+	private void write(File output, List<GistCommentResponse> comments) throws IOException {
+		try {
+			objectMapper.writeValue(output, comments);
+		} catch(IOException e) {
+			if(output.exists()) {
+				Files.delete(output.toPath());
+			}
+			GistError error = new GistError(GistErrorCode.ERR_COMMENTS_NOT_WRITEABLE, "Could not save comments");
+			logger.error(error.getFormattedMessage() + " with path {}", output);
+			throw new GistRepositoryError(error, e);
+		}
+	}
 
+	private File workingCopyFor(File store) {
+		return new File(store.getParent(), store.getName() + workingCopySuffix);
+	}
+
+	/**
+	 * Restores state of <code>to</code> file from <code>from</code> by performing atomic move.
+	 * 
+	 * @param from file
+	 * @param to file
+	 * @return <code>true</code> if the state was restored, <code>false</code> if from file does not exist.
+	 * @throws GistRepositoryError if file could not be restored
+	 * @throws IllegalStateException if to file already exists
+	 */
+	private boolean restoreState(File from, File to) {
+		Preconditions.checkState(!to.exists(), "Target file '" + to.getAbsolutePath() + "' must not exist");
+		if(from.exists()) {
+			try {
+				Files.move(from.toPath(), to.toPath(), StandardCopyOption.ATOMIC_MOVE);
+				logger.warn("{} recreated state from working copy.", from);
+				return true;
+			} catch (IOException e) {
+				GistError error = new GistError(GistErrorCode.ERR_METADATA_NOT_READABLE, "Could not load comments from working copy for this gist");
+				logger.error(error.getFormattedMessage() + " with path {}", to);
+				throw new GistRepositoryError(error, e);
+			}
+		}
+		return false;
+	}
 
 }

rcloud-gist-service/src/main/java/com/mangosolutions/rcloud/rawgist/repository/git/GistMetadata.java

@@ -152,4 +152,74 @@ public Fork getForkOf() {
 		return this.forkOf;
 	}
 
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		result = prime * result + (_public ? 1231 : 1237);
+		result = prime * result + ((additionalProperties == null) ? 0 : additionalProperties.hashCode());
+		result = prime * result + ((createdAt == null) ? 0 : createdAt.hashCode());
+		result = prime * result + ((description == null) ? 0 : description.hashCode());
+		result = prime * result + ((forkOf == null) ? 0 : forkOf.hashCode());
+		result = prime * result + ((forks == null) ? 0 : forks.hashCode());
+		result = prime * result + ((id == null) ? 0 : id.hashCode());
+		result = prime * result + ((owner == null) ? 0 : owner.hashCode());
+		result = prime * result + ((updatedAt == null) ? 0 : updatedAt.hashCode());
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		GistMetadata other = (GistMetadata) obj;
+		if (_public != other._public)
+			return false;
+		if (additionalProperties == null) {
+			if (other.additionalProperties != null)
+				return false;
+		} else if (!additionalProperties.equals(other.additionalProperties))
+			return false;
+		if (createdAt == null) {
+			if (other.createdAt != null)
+				return false;
+		} else if (!createdAt.equals(other.createdAt))
+			return false;
+		if (description == null) {
+			if (other.description != null)
+				return false;
+		} else if (!description.equals(other.description))
+			return false;
+		if (forkOf == null) {
+			if (other.forkOf != null)
+				return false;
+		} else if (!forkOf.equals(other.forkOf))
+			return false;
+		if (forks == null) {
+			if (other.forks != null)
+				return false;
+		} else if (!forks.equals(other.forks))
+			return false;
+		if (id == null) {
+			if (other.id != null)
+				return false;
+		} else if (!id.equals(other.id))
+			return false;
+		if (owner == null) {
+			if (other.owner != null)
+				return false;
+		} else if (!owner.equals(other.owner))
+			return false;
+		if (updatedAt == null) {
+			if (other.updatedAt != null)
+				return false;
+		} else if (!updatedAt.equals(other.updatedAt))
+			return false;
+		return true;
+	}
+
 }

rcloud-gist-service/src/main/java/com/mangosolutions/rcloud/rawgist/repository/git/GistMetadataStore.java

@@ -8,15 +8,19 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.StandardCopyOption;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.cache.annotation.CachePut;
 import org.springframework.cache.annotation.Cacheable;
 import org.springframework.stereotype.Component;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.base.Preconditions;
 import com.mangosolutions.rcloud.rawgist.repository.GistError;
 import com.mangosolutions.rcloud.rawgist.repository.GistErrorCode;
 import com.mangosolutions.rcloud.rawgist.repository.GistRepositoryError;
@@ -29,6 +33,9 @@ public class GistMetadataStore implements MetadataStore {
 	@Autowired
 	private ObjectMapper objectMapper;
 
+	@Value("${gists.metadatastore.workingCopySuffix:.tmp}")
+	private String workingCopySuffix = ".tmp";
+
 	public GistMetadataStore() {
 		this.objectMapper = new ObjectMapper();
 	}
@@ -45,13 +52,13 @@ public ObjectMapper getObjectMapper() {
 	public void setObjectMapper(ObjectMapper objectMapper) {
 		this.objectMapper = objectMapper;
 	}
-
-
+
 	@Override
 	@Cacheable(value = "metadatastore", key = "#store.getAbsolutePath()")
 	public GistMetadata load(File store) {
 		GistMetadata metadata = null;
-		if(store.exists()) {
+		File workingCopy = workingCopyFor(store);
+		if(store.exists() || restoreState(workingCopy, store)) {
 			try {
 				metadata = objectMapper.readValue(store, GistMetadata.class);
 			} catch (IOException e) {
@@ -69,7 +76,15 @@ public GistMetadata load(File store) {
 	@CachePut(cacheNames = "metadatastore", key = "#store.getAbsolutePath()")
 	public GistMetadata save(File store, GistMetadata metadata) {
 		try {
-			objectMapper.writeValue(store, metadata);
+			File workingCopy = workingCopyFor(store);
+			if(!store.exists()) {
+				restoreState(workingCopy, store);
+			}
+			write(workingCopy, metadata);
+			if(store.exists()) {
+				Files.delete(store.toPath());
+			}
+			Files.move(workingCopy.toPath(), store.toPath(), StandardCopyOption.ATOMIC_MOVE);
 		} catch (IOException e) {
 			GistError error = new GistError(GistErrorCode.ERR_METADATA_NOT_WRITEABLE, "Could not update metadata for gist {}", metadata.getId());
 			logger.error(error.getFormattedMessage() + " with path {}", store);
@@ -78,4 +93,46 @@ public GistMetadata save(File store, GistMetadata metadata) {
 		return metadata;
 	}
 
+
+	private File workingCopyFor(File store) {
+		return new File(store.getParent(), store.getName() + workingCopySuffix);
+	}
+
+	/**
+	 * Restores state of <code>to</code> file from <code>from</code> by performing atomic move.
+	 * 
+	 * @param from file
+	 * @param to file
+	 * @return <code>true</code> if the state was restored, <code>false</code> if from file does not exist.
+	 * @throws GistRepositoryError if file could not be restored
+	 * @throws IllegalStateException if to file already exists
+	 */
+	private boolean restoreState(File from, File to) {
+		Preconditions.checkState(!to.exists(), "Target file '" + to.getAbsolutePath() + "' must not exist");
+		if(from.exists()) {
+			try {
+				Files.move(from.toPath(), to.toPath(), StandardCopyOption.ATOMIC_MOVE);
+				logger.warn("{} recreated state from working copy.", from);
+				return true;
+			} catch (IOException e) {
+				GistError error = new GistError(GistErrorCode.ERR_METADATA_NOT_READABLE, "Could not load metadata from working copy for this gist");
+				logger.error(error.getFormattedMessage() + " with path {}", to);
+				throw new GistRepositoryError(error, e);
+			}
+		}
+		return false;
+	}
+
+	private void write(File output, GistMetadata metadata) throws IOException {
+		try {
+			objectMapper.writeValue(output, metadata);
+		} catch(IOException e) {
+			if(output.exists()) {
+				Files.delete(output.toPath());
+			}
+			GistError error = new GistError(GistErrorCode.ERR_METADATA_NOT_WRITEABLE, "Could not update metadata for gist {}", metadata.getId());
+			logger.error(error.getFormattedMessage() + " with path {}", output);
+			throw new GistRepositoryError(error, e);
+		}
+	}
 }