Github user xndai commented on a diff in the pull request:
https://github.com/apache/orc/pull/134#discussion_r123646956
--- Diff: c++/src/OrcHdfsFile.cc ---
@@ -0,0 +1,170 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "orc/OrcFile.hh"
+
+#include "Adaptor.hh"
+#include "Exceptions.hh"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "hdfspp/hdfspp.h"
+#include "common/uri.h"
+#include "common/hdfs_configuration.h"
+#include "common/configuration_loader.h"
+
+#define BUF_SIZE 1048576 //1 MB
+
+namespace orc {
+
+ class HdfsFileInputStream : public InputStream {
+ private:
+ std::string filename;
+ std::unique_ptr<hdfs::FileHandle> file;
+ std::shared_ptr<hdfs::FileSystem> file_system;
+ uint64_t totalLength;
+
+ public:
+ HdfsFileInputStream(std::string _filename) {
+ filename = _filename ;
+
+ //Building a URI object from the given uri_path
+ hdfs::optional<hdfs::URI> uri =
hdfs::URI::parse_from_string(filename);
+ if (!uri) {
+ throw ParseError("Malformed URI: " + filename);
+ }
+
+ hdfs::Options options;
+ //Setting the config path to the default: "$HADOOP_CONF_DIR" or
"/etc/hadoop/conf"
+ hdfs::ConfigurationLoader loader;
+ //Loading default config files core-site.xml and hdfs-site.xml from
the config path
+ hdfs::optional<hdfs::HdfsConfiguration> config =
loader.LoadDefaultResources<hdfs::HdfsConfiguration>();
+ //TODO: HDFS-9539 - after this is resolved, valid config will always
be returned.
+ if(config){
+ //Loading options from the config
+ options = config->GetOptions();
+ }
+ hdfs::IoService * io_service = hdfs::IoService::New();
+ //Wrapping fs into a shared pointer to guarantee deletion
+ std::shared_ptr<hdfs::FileSystem>
fs(hdfs::FileSystem::New(io_service, "", options));
+ if (!fs) {
+ throw ParseError("Can't create FileSystem object. ");
+ }
+ hdfs::Status status;
+ //Check if the user supplied the host
+ if(!uri.value().get_host().empty()){
+ //If port is supplied we use it, otherwise we use the empty string
so that it will be looked up in configs.
+ std::string port = (uri.value().get_port()) ?
std::to_string(uri.value().get_port().value()) : "";
+ status = fs->Connect(uri.value().get_host(), port);
+ if (!status.ok()) {
+ throw ParseError("Can't connect to " + uri.value().get_host() +
":" + port + ". " + status.ToString());
+ }
+ } else {
+ status = fs->ConnectToDefaultFs();
+ if (!status.ok()) {
+ if(!options.defaultFS.get_host().empty()){
+ throw ParseError("Error connecting to " +
options.defaultFS.str() + ". " + status.ToString());
+ } else {
+ throw ParseError("Error connecting to the cluster: defaultFS
is empty. " + status.ToString());
+ }
+ }
+ }
+
+ if (!fs) {
+ throw ParseError("Can't connect the file system. ");
+ }
+
+ hdfs::FileHandle *file_raw = nullptr;
+ status = fs->Open(uri->get_path(), &file_raw);
+ if (!status.ok()) {
+ throw ParseError("Can't open " + uri->get_path() + ". " +
status.ToString());
+ }
+ //wrapping file_raw into a unique pointer to guarantee deletion
+ std::unique_ptr<hdfs::FileHandle> file_handle(file_raw);
+ file = std::move(file_handle);
+ //transferring the ownership of FileSystem to HdfsFileInputStream to
avoid premature deallocation
+ file_system = fs;
+
+ hdfs::StatInfo stat_info;
+ status = fs->GetFileInfo(uri->get_path(), stat_info);
+ if (!status.ok()) {
+ throw ParseError("Can't stat " + uri->get_path() + ". " +
status.ToString());
+ }
+ totalLength = stat_info.length;
+ }
+
+ ~HdfsFileInputStream();
+
+ uint64_t getLength() const override {
+ return totalLength;
+ }
+
+ uint64_t getNaturalReadSize() const override {
+ return BUF_SIZE;
+ }
+
+ void read(void* buf,
+ uint64_t length,
+ uint64_t offset) override {
+
+ ssize_t total_bytes_read = 0;
+ size_t last_bytes_read = 0;
+
+ if (!buf) {
+ throw ParseError("Buffer is null");
+ }
+
+ hdfs::Status status;
+ char input_buffer[BUF_SIZE];
+ do{
+ //Reading file chunks
+ status = file->PositionRead(input_buffer, sizeof(input_buffer),
offset, &last_bytes_read);
--- End diff --
Why do we need an intermedia buffer here? Can we just pass in "buf" and
"length" into PositionRead()? This way we don't need following memcpy() and can
also simply the logic here.
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