/// <summary>
/// This method must be used to obtain the dir allocation context for a
/// particular value of the context name.
/// </summary>
/// <remarks>
/// This method must be used to obtain the dir allocation context for a
/// particular value of the context name. The context name must be an item
/// defined in the Configuration object for which we want to control the
/// dir allocations (e.g., <code>mapred.local.dir</code>). The method will
/// create a context for that name if it doesn't already exist.
/// </remarks>
private LocalDirAllocator.AllocatorPerContext ObtainContext(string contextCfgItemName
)
{
lock (contexts)
{
LocalDirAllocator.AllocatorPerContext l = contexts[contextCfgItemName];
if (l == null)
{
contexts[contextCfgItemName] = (l = new LocalDirAllocator.AllocatorPerContext(contextCfgItemName
));
}
return(l);
}
}
/// <summary>Get the current directory index for the given configuration item.</summary>
/// <returns>the current directory index for the given configuration item.</returns>
internal virtual int GetCurrentDirectoryIndex()
{
LocalDirAllocator.AllocatorPerContext context = ObtainContext(contextCfgItemName);
return(context.GetCurrentDirectoryIndex());
}
/// <summary>
/// We search through all the configured dirs for the file's existence
/// and return true when we find
/// </summary>
/// <param name="pathStr">the requested file (this will be searched)</param>
/// <param name="conf">the Configuration object</param>
/// <returns>true if files exist. false otherwise</returns>
/// <exception cref="System.IO.IOException"/>
public virtual bool IfExists(string pathStr, Configuration conf)
{
LocalDirAllocator.AllocatorPerContext context = ObtainContext(contextCfgItemName);
return(context.IfExists(pathStr, conf));
}
/// <summary>Creates a temporary file in the local FS.</summary>
/// <remarks>
/// Creates a temporary file in the local FS. Pass size as -1 if not known
/// apriori. We round-robin over the set of disks (via the configured dirs)
/// and select the first complete path which has enough space. A file is
/// created on this directory. The file is guaranteed to go away when the
/// JVM exits.
/// </remarks>
/// <param name="pathStr">prefix for the temporary file</param>
/// <param name="size">the size of the file that is going to be written</param>
/// <param name="conf">the Configuration object</param>
/// <returns>a unique temporary file</returns>
/// <exception cref="System.IO.IOException"/>
public virtual FilePath CreateTmpFileForWrite(string pathStr, long size, Configuration
conf)
{
LocalDirAllocator.AllocatorPerContext context = ObtainContext(contextCfgItemName);
return(context.CreateTmpFileForWrite(pathStr, size, conf));
}
/// <summary>Get a path from the local FS for reading.</summary>
/// <remarks>
/// Get a path from the local FS for reading. We search through all the
/// configured dirs for the file's existence and return the complete
/// path to the file when we find one
/// </remarks>
/// <param name="pathStr">the requested file (this will be searched)</param>
/// <param name="conf">the Configuration object</param>
/// <returns>the complete path to the file on a local disk</returns>
/// <exception cref="System.IO.IOException"/>
public virtual Path GetLocalPathToRead(string pathStr, Configuration conf)
{
LocalDirAllocator.AllocatorPerContext context = ObtainContext(contextCfgItemName);
return(context.GetLocalPathToRead(pathStr, conf));
}
/// <summary>Get a path from the local FS.</summary>
/// <remarks>
/// Get a path from the local FS. Pass size as
/// SIZE_UNKNOWN if not known apriori. We
/// round-robin over the set of disks (via the configured dirs) and return
/// the first complete path which has enough space
/// </remarks>
/// <param name="pathStr">
/// the requested path (this will be created on the first
/// available disk)
/// </param>
/// <param name="size">the size of the file that is going to be written</param>
/// <param name="conf">the Configuration object</param>
/// <param name="checkWrite">ensure that the path is writable</param>
/// <returns>the complete path to the file on a local disk</returns>
/// <exception cref="System.IO.IOException"/>
public virtual Path GetLocalPathForWrite(string pathStr, long size, Configuration
conf, bool checkWrite)
{
LocalDirAllocator.AllocatorPerContext context = ObtainContext(contextCfgItemName);
return(context.GetLocalPathForWrite(pathStr, size, conf, checkWrite));
}
