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rocksdb/hdfs/hdfs.h

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// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
#ifndef LIBHDFS_HDFS_H
#define LIBHDFS_HDFS_H
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <errno.h>
#include <jni.h>
#ifndef O_RDONLY
#define O_RDONLY 1
#endif
#ifndef O_WRONLY
#define O_WRONLY 2
#endif
#ifndef EINTERNAL
#define EINTERNAL 255
#endif
/** All APIs set errno to meaningful values */
#ifdef __cplusplus
extern "C" {
#endif
/**
* Some utility decls used in libhdfs.
*/
typedef int32_t tSize; /// size of data for read/write io ops
typedef time_t tTime; /// time type in seconds
typedef int64_t tOffset;/// offset within the file
typedef uint16_t tPort; /// port
typedef enum tObjectKind {
kObjectKindFile = 'F',
kObjectKindDirectory = 'D',
} tObjectKind;
/**
* The C reflection of org.apache.org.hadoop.FileSystem .
*/
typedef void* hdfsFS;
/**
* The C equivalent of org.apache.org.hadoop.FSData(Input|Output)Stream .
*/
enum hdfsStreamType
{
UNINITIALIZED = 0,
INPUT = 1,
OUTPUT = 2,
};
/**
* The 'file-handle' to a file in hdfs.
*/
struct hdfsFile_internal {
void* file;
enum hdfsStreamType type;
};
typedef struct hdfsFile_internal* hdfsFile;
/**
* hdfsConnectAsUser - Connect to a hdfs file system as a specific user
* Connect to the hdfs.
* @param host A string containing either a host name, or an ip address
* of the namenode of a hdfs cluster. 'host' should be passed as NULL if
* you want to connect to local filesystem. 'host' should be passed as
* 'default' (and port as 0) to used the 'configured' filesystem
* (core-site/core-default.xml).
* @param port The port on which the server is listening.
* @param user the user name (this is hadoop domain user). Or NULL is equivelant to hhdfsConnect(host, port)
* @param groups the groups (these are hadoop domain groups)
* @return Returns a handle to the filesystem or NULL on error.
*/
hdfsFS hdfsConnectAsUser(const char* host, tPort port, const char *user , const char *groups[], int groups_size );
/**
* hdfsConnect - Connect to a hdfs file system.
* Connect to the hdfs.
* @param host A string containing either a host name, or an ip address
* of the namenode of a hdfs cluster. 'host' should be passed as NULL if
* you want to connect to local filesystem. 'host' should be passed as
* 'default' (and port as 0) to used the 'configured' filesystem
* (core-site/core-default.xml).
* @param port The port on which the server is listening.
* @return Returns a handle to the filesystem or NULL on error.
*/
hdfsFS hdfsConnect(const char* host, tPort port);
/**
* This are the same as hdfsConnectAsUser except that every invocation returns a new FileSystem handle.
* Applications should call a hdfsDisconnect for every call to hdfsConnectAsUserNewInstance.
*/
hdfsFS hdfsConnectAsUserNewInstance(const char* host, tPort port, const char *user , const char *groups[], int groups_size );
hdfsFS hdfsConnectNewInstance(const char* host, tPort port);
hdfsFS hdfsConnectPath(const char* uri);
/**
* hdfsDisconnect - Disconnect from the hdfs file system.
* Disconnect from hdfs.
* @param fs The configured filesystem handle.
* @return Returns 0 on success, -1 on error.
*/
int hdfsDisconnect(hdfsFS fs);
/**
* hdfsOpenFile - Open a hdfs file in given mode.
* @param fs The configured filesystem handle.
* @param path The full path to the file.
* @param flags - an | of bits/fcntl.h file flags - supported flags are O_RDONLY, O_WRONLY (meaning create or overwrite i.e., implies O_TRUNCAT),
* O_WRONLY|O_APPEND. Other flags are generally ignored other than (O_RDWR || (O_EXCL & O_CREAT)) which return NULL and set errno equal ENOTSUP.
* @param bufferSize Size of buffer for read/write - pass 0 if you want
* to use the default configured values.
* @param replication Block replication - pass 0 if you want to use
* the default configured values.
* @param blocksize Size of block - pass 0 if you want to use the
* default configured values.
* @return Returns the handle to the open file or NULL on error.
*/
hdfsFile hdfsOpenFile(hdfsFS fs, const char* path, int flags,
int bufferSize, short replication, tSize blocksize);
/**
* hdfsCloseFile - Close an open file.
* @param fs The configured filesystem handle.
* @param file The file handle.
* @return Returns 0 on success, -1 on error.
*/
int hdfsCloseFile(hdfsFS fs, hdfsFile file);
/**
* hdfsExists - Checks if a given path exsits on the filesystem
* @param fs The configured filesystem handle.
* @param path The path to look for
* @return Returns 0 on exists, 1 on non-exists, -1/-2 on error.
*/
int hdfsExists(hdfsFS fs, const char *path);
/**
* hdfsSeek - Seek to given offset in file.
* This works only for files opened in read-only mode.
* @param fs The configured filesystem handle.
* @param file The file handle.
* @param desiredPos Offset into the file to seek into.
* @return Returns 0 on success, -1 on error.
*/
int hdfsSeek(hdfsFS fs, hdfsFile file, tOffset desiredPos);
/**
* hdfsTell - Get the current offset in the file, in bytes.
* @param fs The configured filesystem handle.
* @param file The file handle.
* @return Current offset, -1 on error.
*/
tOffset hdfsTell(hdfsFS fs, hdfsFile file);
/**
* hdfsRead - Read data from an open file.
* @param fs The configured filesystem handle.
* @param file The file handle.
* @param buffer The buffer to copy read bytes into.
* @param length The length of the buffer.
* @return Returns the number of bytes actually read, possibly less
* than than length;-1 on error.
*/
tSize hdfsRead(hdfsFS fs, hdfsFile file, void* buffer, tSize length);
/**
* hdfsPread - Positional read of data from an open file.
* @param fs The configured filesystem handle.
* @param file The file handle.
* @param position Position from which to read
* @param buffer The buffer to copy read bytes into.
* @param length The length of the buffer.
* @return Returns the number of bytes actually read, possibly less than
* than length;-1 on error.
*/
tSize hdfsPread(hdfsFS fs, hdfsFile file, tOffset position,
void* buffer, tSize length);
/**
* hdfsWrite - Write data into an open file.
* @param fs The configured filesystem handle.
* @param file The file handle.
* @param buffer The data.
* @param length The no. of bytes to write.
* @return Returns the number of bytes written, -1 on error.
*/
tSize hdfsWrite(hdfsFS fs, hdfsFile file, const void* buffer,
tSize length);
/**
* hdfsWrite - Flush the data.
* @param fs The configured filesystem handle.
* @param file The file handle.
* @return Returns 0 on success, -1 on error.
*/
int hdfsFlush(hdfsFS fs, hdfsFile file);
/**
* hdfsSync - Sync the data to persistent store.
* @param fs The configured filesystem handle.
* @param file The file handle.
* @return Returns 0 on success, -1 on error.
*/
int hdfsSync(hdfsFS fs, hdfsFile file);
/**
* hdfsGetNumReplicasInPipeline - get number of remaining replicas in
* pipeline
* @param fs The configured filesystem handle
* @param file the file handle
* @return returns the # of datanodes in the write pipeline; -1 on error
*/
int hdfsGetNumCurrentReplicas(hdfsFS, hdfsFile file);
/**
* hdfsAvailable - Number of bytes that can be read from this
* input stream without blocking.
* @param fs The configured filesystem handle.
* @param file The file handle.
* @return Returns available bytes; -1 on error.
*/
int hdfsAvailable(hdfsFS fs, hdfsFile file);
/**
* hdfsCopy - Copy file from one filesystem to another.
* @param srcFS The handle to source filesystem.
* @param src The path of source file.
* @param dstFS The handle to destination filesystem.
* @param dst The path of destination file.
* @return Returns 0 on success, -1 on error.
*/
int hdfsCopy(hdfsFS srcFS, const char* src, hdfsFS dstFS, const char* dst);
/**
* hdfsMove - Move file from one filesystem to another.
* @param srcFS The handle to source filesystem.
* @param src The path of source file.
* @param dstFS The handle to destination filesystem.
* @param dst The path of destination file.
* @return Returns 0 on success, -1 on error.
*/
int hdfsMove(hdfsFS srcFS, const char* src, hdfsFS dstFS, const char* dst);
/**
* hdfsDelete - Delete file.
* @param fs The configured filesystem handle.
* @param path The path of the file.
* @return Returns 0 on success, -1 on error.
*/
int hdfsDelete(hdfsFS fs, const char* path);
/**
* hdfsRename - Rename file.
* @param fs The configured filesystem handle.
* @param oldPath The path of the source file.
* @param newPath The path of the destination file.
* @return Returns 0 on success, -1 on error.
*/
int hdfsRename(hdfsFS fs, const char* oldPath, const char* newPath);
/**
* hdfsGetWorkingDirectory - Get the current working directory for
* the given filesystem.
* @param fs The configured filesystem handle.
* @param buffer The user-buffer to copy path of cwd into.
* @param bufferSize The length of user-buffer.
* @return Returns buffer, NULL on error.
*/
char* hdfsGetWorkingDirectory(hdfsFS fs, char *buffer, size_t bufferSize);
/**
* hdfsSetWorkingDirectory - Set the working directory. All relative
* paths will be resolved relative to it.
* @param fs The configured filesystem handle.
* @param path The path of the new 'cwd'.
* @return Returns 0 on success, -1 on error.
*/
int hdfsSetWorkingDirectory(hdfsFS fs, const char* path);
/**
* hdfsCreateDirectory - Make the given file and all non-existent
* parents into directories.
* @param fs The configured filesystem handle.
* @param path The path of the directory.
* @return Returns 0 on success, -1 on error.
*/
int hdfsCreateDirectory(hdfsFS fs, const char* path);
/**
* hdfsSetReplication - Set the replication of the specified
* file to the supplied value
* @param fs The configured filesystem handle.
* @param path The path of the file.
* @return Returns 0 on success, -1 on error.
*/
int hdfsSetReplication(hdfsFS fs, const char* path, int16_t replication);
/**
* hdfsFileInfo - Information about a file/directory.
*/
typedef struct {
tObjectKind mKind; /* file or directory */
char *mName; /* the name of the file */
tTime mLastMod; /* the last modification time for the file in seconds */
tOffset mSize; /* the size of the file in bytes */
short mReplication; /* the count of replicas */
tOffset mBlockSize; /* the block size for the file */
char *mOwner; /* the owner of the file */
char *mGroup; /* the group associated with the file */
short mPermissions; /* the permissions associated with the file */
tTime mLastAccess; /* the last access time for the file in seconds */
} hdfsFileInfo;
/**
* hdfsListDirectory - Get list of files/directories for a given
* directory-path. hdfsFreeFileInfo should be called to deallocate memory if
* the function returns non-NULL value.
* @param fs The configured filesystem handle.
* @param path The path of the directory.
* @param numEntries Set to the number of files/directories in path.
* @return Returns a dynamically-allocated array of hdfsFileInfo
* objects; NULL if empty or on error.
* on error, numEntries will be -1.
*/
hdfsFileInfo *hdfsListDirectory(hdfsFS fs, const char* path,
int *numEntries);
/**
* hdfsGetPathInfo - Get information about a path as a (dynamically
* allocated) single hdfsFileInfo struct. hdfsFreeFileInfo should be
* called when the pointer is no longer needed.
* @param fs The configured filesystem handle.
* @param path The path of the file.
* @return Returns a dynamically-allocated hdfsFileInfo object;
* NULL on error.
*/
hdfsFileInfo *hdfsGetPathInfo(hdfsFS fs, const char* path);
/**
* hdfsFreeFileInfo - Free up the hdfsFileInfo array (including fields)
* @param hdfsFileInfo The array of dynamically-allocated hdfsFileInfo
* objects.
* @param numEntries The size of the array.
*/
void hdfsFreeFileInfo(hdfsFileInfo *hdfsFileInfo, int numEntries);
/**
* hdfsGetHosts - Get hostnames where a particular block (determined by
* pos & blocksize) of a file is stored. The last element in the array
* is NULL. Due to replication, a single block could be present on
* multiple hosts.
* @param fs The configured filesystem handle.
* @param path The path of the file.
* @param start The start of the block.
* @param length The length of the block.
* @return Returns a dynamically-allocated 2-d array of blocks-hosts;
* NULL on error.
*/
char*** hdfsGetHosts(hdfsFS fs, const char* path,
tOffset start, tOffset length);
/**
* hdfsFreeHosts - Free up the structure returned by hdfsGetHosts
* @param hdfsFileInfo The array of dynamically-allocated hdfsFileInfo
* objects.
* @param numEntries The size of the array.
*/
void hdfsFreeHosts(char ***blockHosts);
/**
* hdfsGetDefaultBlockSize - Get the optimum blocksize.
* @param fs The configured filesystem handle.
* @return Returns the blocksize; -1 on error.
*/
tOffset hdfsGetDefaultBlockSize(hdfsFS fs);
/**
* hdfsGetCapacity - Return the raw capacity of the filesystem.
* @param fs The configured filesystem handle.
* @return Returns the raw-capacity; -1 on error.
*/
tOffset hdfsGetCapacity(hdfsFS fs);
/**
* hdfsGetUsed - Return the total raw size of all files in the filesystem.
* @param fs The configured filesystem handle.
* @return Returns the total-size; -1 on error.
*/
tOffset hdfsGetUsed(hdfsFS fs);
/**
* hdfsChown
* @param fs The configured filesystem handle.
* @param path the path to the file or directory
* @param owner this is a string in Hadoop land. Set to null or "" if only setting group
* @param group this is a string in Hadoop land. Set to null or "" if only setting user
* @return 0 on success else -1
*/
int hdfsChown(hdfsFS fs, const char* path, const char *owner, const char *group);
/**
* hdfsChmod
* @param fs The configured filesystem handle.
* @param path the path to the file or directory
* @param mode the bitmask to set it to
* @return 0 on success else -1
*/
int hdfsChmod(hdfsFS fs, const char* path, short mode);
/**
* hdfsUtime
* @param fs The configured filesystem handle.
* @param path the path to the file or directory
* @param mtime new modification time or 0 for only set access time in seconds
* @param atime new access time or 0 for only set modification time in seconds
* @return 0 on success else -1
*/
int hdfsUtime(hdfsFS fs, const char* path, tTime mtime, tTime atime);
#ifdef __cplusplus
}
#endif
#endif /*LIBHDFS_HDFS_H*/
/**
* vim: ts=4: sw=4: et
*/
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