/** * 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. */ #ifndef LIBHDFS_HDFS_H #define LIBHDFS_HDFS_H #include /* for EINTERNAL, etc. */ #include /* for O_RDONLY, O_WRONLY */ #include /* for uint64_t, etc. */ #include /* for time_t */ /* * Support export of DLL symbols during libhdfs build, and import of DLL symbols * during client application build. A client application may optionally define * symbol LIBHDFS_DLL_IMPORT in its build. This is not strictly required, but * the compiler can produce more efficient code with it. */ #ifdef WIN32 #ifdef LIBHDFS_DLL_EXPORT #define LIBHDFS_EXTERNAL __declspec(dllexport) #elif LIBHDFS_DLL_IMPORT #define LIBHDFS_EXTERNAL __declspec(dllimport) #else #define LIBHDFS_EXTERNAL #endif #else #ifdef LIBHDFS_DLL_EXPORT #define LIBHDFS_EXTERNAL __attribute__((visibility("default"))) #elif LIBHDFS_DLL_IMPORT #define LIBHDFS_EXTERNAL __attribute__((visibility("default"))) #else #define LIBHDFS_EXTERNAL #endif #endif #ifndef O_RDONLY #define O_RDONLY 1 #endif #ifndef O_WRONLY #define O_WRONLY 2 #endif #ifndef EINTERNAL #define EINTERNAL 255 #endif #define ELASTIC_BYTE_BUFFER_POOL_CLASS \ "org/apache/hadoop/io/ElasticByteBufferPool" /** All APIs set errno to meaningful values */ #ifdef __cplusplus extern "C" { #endif /** * Some utility decls used in libhdfs. */ struct hdfsBuilder; 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 . */ struct hdfs_internal; typedef struct hdfs_internal* hdfsFS; struct hdfsFile_internal; typedef struct hdfsFile_internal* hdfsFile; struct hadoopRzOptions; struct hadoopRzBuffer; /** * Determine if a file is open for read. * * @param file The HDFS file * @return 1 if the file is open for read; 0 otherwise */ LIBHDFS_EXTERNAL int hdfsFileIsOpenForRead(hdfsFile file); /** * Determine if a file is open for write. * * @param file The HDFS file * @return 1 if the file is open for write; 0 otherwise */ LIBHDFS_EXTERNAL int hdfsFileIsOpenForWrite(hdfsFile file); struct hdfsReadStatistics { uint64_t totalBytesRead; uint64_t totalLocalBytesRead; uint64_t totalShortCircuitBytesRead; uint64_t totalZeroCopyBytesRead; }; /** * Get read statistics about a file. This is only applicable to files * opened for reading. * * @param file The HDFS file * @param stats (out parameter) on a successful return, the read * statistics. Unchanged otherwise. You must free the * returned statistics with hdfsFileFreeReadStatistics. * @return 0 if the statistics were successfully returned, * -1 otherwise. On a failure, please check errno against * ENOTSUP. webhdfs, LocalFilesystem, and so forth may * not support read statistics. */ LIBHDFS_EXTERNAL int hdfsFileGetReadStatistics(hdfsFile file, struct hdfsReadStatistics **stats); /** * @param stats HDFS read statistics for a file. * * @return the number of remote bytes read. */ LIBHDFS_EXTERNAL int64_t hdfsReadStatisticsGetRemoteBytesRead( const struct hdfsReadStatistics *stats); /** * Clear the read statistics for a file. * * @param file The file to clear the read statistics of. * * @return 0 on success; the error code otherwise. * EINVAL: the file is not open for reading. * ENOTSUP: the file does not support clearing the read * statistics. * Errno will also be set to this code on failure. */ LIBHDFS_EXTERNAL int hdfsFileClearReadStatistics(hdfsFile file); /** * Free some HDFS read statistics. * * @param stats The HDFS read statistics to free. */ LIBHDFS_EXTERNAL void hdfsFileFreeReadStatistics(struct hdfsReadStatistics *stats); /** * hdfsConnectAsUser - Connect to a hdfs file system as a specific user * Connect to the hdfs. * @param nn The NameNode. See hdfsBuilderSetNameNode for details. * @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) * @return Returns a handle to the filesystem or NULL on error. * @deprecated Use hdfsBuilderConnect instead. */ LIBHDFS_EXTERNAL hdfsFS hdfsConnectAsUser(const char* nn, tPort port, const char *user); /** * hdfsConnect - Connect to a hdfs file system. * Connect to the hdfs. * @param nn The NameNode. See hdfsBuilderSetNameNode for details. * @param port The port on which the server is listening. * @return Returns a handle to the filesystem or NULL on error. * @deprecated Use hdfsBuilderConnect instead. */ LIBHDFS_EXTERNAL hdfsFS hdfsConnect(const char* nn, tPort port); /** * hdfsConnect - Connect to an hdfs file system. * * Forces a new instance to be created * * @param nn The NameNode. See hdfsBuilderSetNameNode for details. * @param port The port on which the server is listening. * @param user The user name to use when connecting * @return Returns a handle to the filesystem or NULL on error. * @deprecated Use hdfsBuilderConnect instead. */ LIBHDFS_EXTERNAL hdfsFS hdfsConnectAsUserNewInstance(const char* nn, tPort port, const char *user ); /** * hdfsConnect - Connect to an hdfs file system. * * Forces a new instance to be created * * @param nn The NameNode. See hdfsBuilderSetNameNode for details. * @param port The port on which the server is listening. * @return Returns a handle to the filesystem or NULL on error. * @deprecated Use hdfsBuilderConnect instead. */ LIBHDFS_EXTERNAL hdfsFS hdfsConnectNewInstance(const char* nn, tPort port); /** * Connect to HDFS using the parameters defined by the builder. * * The HDFS builder will be freed, whether or not the connection was * successful. * * Every successful call to hdfsBuilderConnect should be matched with a call * to hdfsDisconnect, when the hdfsFS is no longer needed. * * @param bld The HDFS builder * @return Returns a handle to the filesystem, or NULL on error. */ LIBHDFS_EXTERNAL hdfsFS hdfsBuilderConnect(struct hdfsBuilder *bld); /** * Create an HDFS builder. * * @return The HDFS builder, or NULL on error. */ LIBHDFS_EXTERNAL struct hdfsBuilder *hdfsNewBuilder(void); /** * Force the builder to always create a new instance of the FileSystem, * rather than possibly finding one in the cache. * * @param bld The HDFS builder */ LIBHDFS_EXTERNAL void hdfsBuilderSetForceNewInstance(struct hdfsBuilder *bld); /** * Set the HDFS NameNode to connect to. * * @param bld The HDFS builder * @param nn The NameNode to use. * * If the string given is 'default', the default NameNode * configuration will be used (from the XML configuration files) * * If NULL is given, a LocalFileSystem will be created. * * If the string starts with a protocol type such as file:// or * hdfs://, this protocol type will be used. If not, the * hdfs:// protocol type will be used. * * You may specify a NameNode port in the usual way by * passing a string of the format hdfs://:. * Alternately, you may set the port with * hdfsBuilderSetNameNodePort. However, you must not pass the * port in two different ways. */ LIBHDFS_EXTERNAL void hdfsBuilderSetNameNode(struct hdfsBuilder *bld, const char *nn); /** * Set the port of the HDFS NameNode to connect to. * * @param bld The HDFS builder * @param port The port. */ LIBHDFS_EXTERNAL void hdfsBuilderSetNameNodePort(struct hdfsBuilder *bld, tPort port); /** * Set the username to use when connecting to the HDFS cluster. * * @param bld The HDFS builder * @param userName The user name. The string will be shallow-copied. */ LIBHDFS_EXTERNAL void hdfsBuilderSetUserName(struct hdfsBuilder *bld, const char *userName); /** * Set the path to the Kerberos ticket cache to use when connecting to * the HDFS cluster. * * @param bld The HDFS builder * @param kerbTicketCachePath The Kerberos ticket cache path. The string * will be shallow-copied. */ LIBHDFS_EXTERNAL void hdfsBuilderSetKerbTicketCachePath(struct hdfsBuilder *bld, const char *kerbTicketCachePath); /** * Free an HDFS builder. * * It is normally not necessary to call this function since * hdfsBuilderConnect frees the builder. * * @param bld The HDFS builder */ LIBHDFS_EXTERNAL void hdfsFreeBuilder(struct hdfsBuilder *bld); /** * Set a configuration string for an HdfsBuilder. * * @param key The key to set. * @param val The value, or NULL to set no value. * This will be shallow-copied. You are responsible for * ensuring that it remains valid until the builder is * freed. * * @return 0 on success; nonzero error code otherwise. */ LIBHDFS_EXTERNAL int hdfsBuilderConfSetStr(struct hdfsBuilder *bld, const char *key, const char *val); /** * Get a configuration string. * * @param key The key to find * @param val (out param) The value. This will be set to NULL if the * key isn't found. You must free this string with * hdfsConfStrFree. * * @return 0 on success; nonzero error code otherwise. * Failure to find the key is not an error. */ LIBHDFS_EXTERNAL int hdfsConfGetStr(const char *key, char **val); /** * Get a configuration integer. * * @param key The key to find * @param val (out param) The value. This will NOT be changed if the * key isn't found. * * @return 0 on success; nonzero error code otherwise. * Failure to find the key is not an error. */ LIBHDFS_EXTERNAL int hdfsConfGetInt(const char *key, int32_t *val); /** * Free a configuration string found with hdfsConfGetStr. * * @param val A configuration string obtained from hdfsConfGetStr */ LIBHDFS_EXTERNAL void hdfsConfStrFree(char *val); /** * hdfsDisconnect - Disconnect from the hdfs file system. * Disconnect from hdfs. * @param fs The configured filesystem handle. * @return Returns 0 on success, -1 on error. * Even if there is an error, the resources associated with the * hdfsFS will be freed. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL hdfsFile hdfsOpenFile(hdfsFS fs, const char* path, int flags, int bufferSize, short replication, tSize blocksize); /** * hdfsTruncateFile - Truncate a hdfs file to given lenght. * @param fs The configured filesystem handle. * @param path The full path to the file. * @param newlength The size the file is to be truncated to * @return 1 if the file has been truncated to the desired newlength * and is immediately available to be reused for write operations * such as append. * 0 if a background process of adjusting the length of the last * block has been started, and clients should wait for it to * complete before proceeding with further file updates. * -1 on error. */ LIBHDFS_EXTERNAL int hdfsTruncateFile(hdfsFS fs, const char* path, tOffset newlength); /** * hdfsUnbufferFile - Reduce the buffering done on a file. * * @param file The file to unbuffer. * @return 0 on success * ENOTSUP if the file does not support unbuffering * Errno will also be set to this value. */ LIBHDFS_EXTERNAL int hdfsUnbufferFile(hdfsFile file); /** * hdfsCloseFile - Close an open file. * @param fs The configured filesystem handle. * @param file The file handle. * @return Returns 0 on success, -1 on error. * On error, errno will be set appropriately. * If the hdfs file was valid, the memory associated with it will * be freed at the end of this call, even if there was an I/O * error. */ LIBHDFS_EXTERNAL 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 success, -1 on error. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL 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 On success, a positive number indicating how many bytes * were read. * On end-of-file, 0. * On error, -1. Errno will be set to the error code. * Just like the POSIX read function, hdfsRead will return -1 * and set errno to EINTR if data is temporarily unavailable, * but we are not yet at the end of the file. */ LIBHDFS_EXTERNAL 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 See hdfsRead */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL int hdfsFlush(hdfsFS fs, hdfsFile file); /** * hdfsHFlush - Flush out the data in client's user buffer. After the * return of this call, new readers will see the data. * @param fs configured filesystem handle * @param file file handle * @return 0 on success, -1 on error and sets errno */ LIBHDFS_EXTERNAL int hdfsHFlush(hdfsFS fs, hdfsFile file); /** * hdfsHSync - Similar to posix fsync, Flush out the data in client's * user buffer. all the way to the disk device (but the disk may have * it in its cache). * @param fs configured filesystem handle * @param file file handle * @return 0 on success, -1 on error and sets errno */ LIBHDFS_EXTERNAL int hdfsHSync(hdfsFS fs, 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. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL 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. * @param recursive if path is a directory and set to * non-zero, the directory is deleted else throws an exception. In * case of a file the recursive argument is irrelevant. * @return Returns 0 on success, -1 on error. */ LIBHDFS_EXTERNAL int hdfsDelete(hdfsFS fs, const char* path, int recursive); /** * 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. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL 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. * @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 on error or empty directory. * errno is set to non-zero on error or zero on success. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL void hdfsFreeFileInfo(hdfsFileInfo *hdfsFileInfo, int numEntries); /** * hdfsFileIsEncrypted: determine if a file is encrypted based on its * hdfsFileInfo. * @return -1 if there was an error (errno will be set), 0 if the file is * not encrypted, 1 if the file is encrypted. */ LIBHDFS_EXTERNAL int hdfsFileIsEncrypted(hdfsFileInfo *hdfsFileInfo); /** * 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. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL void hdfsFreeHosts(char ***blockHosts); /** * hdfsGetDefaultBlockSize - Get the default blocksize. * * @param fs The configured filesystem handle. * @deprecated Use hdfsGetDefaultBlockSizeAtPath instead. * * @return Returns the default blocksize, or -1 on error. */ LIBHDFS_EXTERNAL tOffset hdfsGetDefaultBlockSize(hdfsFS fs); /** * hdfsGetDefaultBlockSizeAtPath - Get the default blocksize at the * filesystem indicated by a given path. * * @param fs The configured filesystem handle. * @param path The given path will be used to locate the actual * filesystem. The full path does not have to exist. * * @return Returns the default blocksize, or -1 on error. */ LIBHDFS_EXTERNAL tOffset hdfsGetDefaultBlockSizeAtPath(hdfsFS fs, const char *path); /** * hdfsGetCapacity - Return the raw capacity of the filesystem. * @param fs The configured filesystem handle. * @return Returns the raw-capacity; -1 on error. */ LIBHDFS_EXTERNAL 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. */ LIBHDFS_EXTERNAL tOffset hdfsGetUsed(hdfsFS fs); /** * Change the user and/or group of a file or directory. * * @param fs The configured filesystem handle. * @param path the path to the file or directory * @param owner User string. Set to NULL for 'no change' * @param group Group string. Set to NULL for 'no change' * @return 0 on success else -1 */ LIBHDFS_EXTERNAL 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 */ LIBHDFS_EXTERNAL 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 -1 for no change * @param atime new access time or -1 for no change * @return 0 on success else -1 */ LIBHDFS_EXTERNAL int hdfsUtime(hdfsFS fs, const char* path, tTime mtime, tTime atime); /** * Allocate a zero-copy options structure. * * You must free all options structures allocated with this function using * hadoopRzOptionsFree. * * @return A zero-copy options structure, or NULL if one could * not be allocated. If NULL is returned, errno will * contain the error number. */ LIBHDFS_EXTERNAL struct hadoopRzOptions *hadoopRzOptionsAlloc(void); /** * Determine whether we should skip checksums in read0. * * @param opts The options structure. * @param skip Nonzero to skip checksums sometimes; zero to always * check them. * * @return 0 on success; -1 plus errno on failure. */ LIBHDFS_EXTERNAL int hadoopRzOptionsSetSkipChecksum( struct hadoopRzOptions *opts, int skip); /** * Set the ByteBufferPool to use with read0. * * @param opts The options structure. * @param className If this is NULL, we will not use any * ByteBufferPool. If this is non-NULL, it will be * treated as the name of the pool class to use. * For example, you can use * ELASTIC_BYTE_BUFFER_POOL_CLASS. * * @return 0 if the ByteBufferPool class was found and * instantiated; * -1 plus errno otherwise. */ LIBHDFS_EXTERNAL int hadoopRzOptionsSetByteBufferPool( struct hadoopRzOptions *opts, const char *className); /** * Free a hadoopRzOptionsFree structure. * * @param opts The options structure to free. * Any associated ByteBufferPool will also be freed. */ LIBHDFS_EXTERNAL void hadoopRzOptionsFree(struct hadoopRzOptions *opts); /** * Perform a byte buffer read. * If possible, this will be a zero-copy (mmap) read. * * @param file The file to read from. * @param opts An options structure created by hadoopRzOptionsAlloc. * @param maxLength The maximum length to read. We may read fewer bytes * than this length. * * @return On success, we will return a new hadoopRzBuffer. * This buffer will continue to be valid and readable * until it is released by readZeroBufferFree. Failure to * release a buffer will lead to a memory leak. * You can access the data within the hadoopRzBuffer with * hadoopRzBufferGet. If you have reached EOF, the data * within the hadoopRzBuffer will be NULL. You must still * free hadoopRzBuffer instances containing NULL. * * On failure, we will return NULL plus an errno code. * errno = EOPNOTSUPP indicates that we could not do a * zero-copy read, and there was no ByteBufferPool * supplied. */ LIBHDFS_EXTERNAL struct hadoopRzBuffer* hadoopReadZero(hdfsFile file, struct hadoopRzOptions *opts, int32_t maxLength); /** * Determine the length of the buffer returned from readZero. * * @param buffer a buffer returned from readZero. * @return the length of the buffer. */ LIBHDFS_EXTERNAL int32_t hadoopRzBufferLength(const struct hadoopRzBuffer *buffer); /** * Get a pointer to the raw buffer returned from readZero. * * To find out how many bytes this buffer contains, call * hadoopRzBufferLength. * * @param buffer a buffer returned from readZero. * @return a pointer to the start of the buffer. This will be * NULL when end-of-file has been reached. */ LIBHDFS_EXTERNAL const void *hadoopRzBufferGet(const struct hadoopRzBuffer *buffer); /** * Release a buffer obtained through readZero. * * @param file The hdfs stream that created this buffer. This must be * the same stream you called hadoopReadZero on. * @param buffer The buffer to release. */ LIBHDFS_EXTERNAL void hadoopRzBufferFree(hdfsFile file, struct hadoopRzBuffer *buffer); #ifdef __cplusplus } #endif #undef LIBHDFS_EXTERNAL #endif /*LIBHDFS_HDFS_H*/ /** * vim: ts=4: sw=4: et */