/**
* Read the schema from json metadata file If isSchemaOn parameter is false, the errors are
* suppressed and logged
*
* @param location
* @param job
* @param isSchemaOn
* @return schema
* @throws IOException
*/
public ResourceSchema getSchema(String location, Job job, boolean isSchemaOn) throws IOException {
Configuration conf = job.getConfiguration();
Set<ElementDescriptor> schemaFileSet = null;
try {
schemaFileSet = findMetaFile(location, schemaFileName, conf);
} catch (IOException e) {
String msg = "Could not find schema file for " + location;
return nullOrException(isSchemaOn, msg, e);
}
// TODO we assume that all schemas are the same. The question of merging schemas is left open
// for now.
ElementDescriptor schemaFile = null;
if (!schemaFileSet.isEmpty()) {
schemaFile = schemaFileSet.iterator().next();
} else {
String msg = "Could not find schema file for " + location;
return nullOrException(isSchemaOn, msg, null);
}
log.debug("Found schema file: " + schemaFile.toString());
ResourceSchema resourceSchema = null;
try {
resourceSchema = new ObjectMapper().readValue(schemaFile.open(), ResourceSchema.class);
} catch (JsonParseException e) {
String msg = "Unable to load Resource Schema for " + location;
return nullOrException(isSchemaOn, msg, e);
} catch (JsonMappingException e) {
String msg = "Unable to load Resource Schema for " + location;
return nullOrException(isSchemaOn, msg, e);
} catch (IOException e) {
String msg = "Unable to load Resource Schema for " + location;
return nullOrException(isSchemaOn, msg, e);
}
return resourceSchema;
}
/**
* For JsonMetadata stats are considered optional This method suppresses (and logs) errors if they
* are encountered.
*
* @see org.apache.pig.LoadMetadata#getStatistics(String, Job)
*/
@Override
public ResourceStatistics getStatistics(String location, Job job) throws IOException {
Configuration conf = job.getConfiguration();
Set<ElementDescriptor> statFileSet = null;
try {
statFileSet = findMetaFile(location, statFileName, conf);
} catch (IOException e) {
log.warn("could not fine stat file for " + location);
return null;
}
ElementDescriptor statFile = null;
if (!statFileSet.isEmpty()) {
statFile = statFileSet.iterator().next();
} else {
log.warn("Could not find stat file for " + location);
return null;
}
log.debug("Found stat file " + statFile.toString());
ResourceStatistics resourceStats = null;
try {
resourceStats = new ObjectMapper().readValue(statFile.open(), ResourceStatistics.class);
} catch (JsonParseException e) {
log.warn("Unable to load Resource Statistics for " + location);
e.printStackTrace();
} catch (JsonMappingException e) {
log.warn("Unable to load Resource Statistics for " + location);
e.printStackTrace();
} catch (IOException e) {
log.warn("Unable to load Resource Statistics for " + location);
e.printStackTrace();
}
return resourceStats;
}
private boolean exists(ElementDescriptor e) throws IOException {
if (lookupCache.containsKey(e)) {
return lookupCache.get(e);
} else {
boolean res = e.exists();
lookupCache.put(e, res);
return res;
}
}
@Override
public void storeStatistics(ResourceStatistics stats, String location, Job job)
throws IOException {
Configuration conf = job.getConfiguration();
DataStorage storage =
new HDataStorage(new Path(location).toUri(), ConfigurationUtil.toProperties(conf));
ElementDescriptor statFilePath = storage.asElement(location, statFileName);
if (!statFilePath.exists() && stats != null) {
try {
new ObjectMapper().writeValue(statFilePath.create(), stats);
} catch (JsonGenerationException e) {
log.warn("Unable to write Resource Statistics for " + location);
e.printStackTrace();
} catch (JsonMappingException e) {
log.warn("Unable to write Resource Statistics for " + location);
e.printStackTrace();
}
}
}
@Override
public void storeSchema(ResourceSchema schema, String location, Job job) throws IOException {
Configuration conf = job.getConfiguration();
DataStorage storage =
new HDataStorage(new Path(location).toUri(), ConfigurationUtil.toProperties(conf));
ElementDescriptor schemaFilePath = storage.asElement(location, schemaFileName);
if (!schemaFilePath.exists() && schema != null) {
try {
new ObjectMapper().writeValue(schemaFilePath.create(), schema);
} catch (JsonGenerationException e) {
log.warn("Unable to write Resource Statistics for " + location);
e.printStackTrace();
} catch (JsonMappingException e) {
log.warn("Unable to write Resource Statistics for " + location);
e.printStackTrace();
}
}
if (printHeaders) {
ElementDescriptor headerFilePath = storage.asElement(location, headerFileName);
if (!headerFilePath.exists()) {
OutputStream os = headerFilePath.create();
try {
String[] names = schema.fieldNames();
String fn;
for (int i = 0; i < names.length; i++) {
fn = ((names[i] == null) ? ("$" + i) : names[i]);
os.write(fn.getBytes("UTF-8"));
if (i < names.length - 1) {
os.write(fieldDel);
} else {
os.write(recordDel);
}
}
} finally {
os.close();
}
}
}
}
