![]() ![]() fileno (), nbytes = 20 ) 20 # copying certain amount of bytes beginning from an offset > splice ( to_read. fileno (), offset = 10 ) 40 # copying certain amount of bytes > splice ( to_read. fileno ()) 50 # bytes copied # copying file starting from an offset > splice ( to_read. read ()) 50 # copying whole file > splice ( to_read. Usage > from splice import splice # init file objects > to_read = open ( "read.txt" ) # file to read from > to_write = open ( "write.txt", "w+" ) # file to write to > len ( to_read. More information on what each of the flag means can be found on the splice(2) Nbytes: number of bytes to be copied in total, default valueįlags: a bit mask which can be composed by ORing together the following. Offset: offset from where the input file is read from. Out: file descriptor of the file to which data is to be transferred. In: file descriptor of the file from which data is to be read. Not specified, the whole of in is copied over to out. Position of in and the position of in is updated. If offset is not specified, the bytes are read from the current When the end of file is reached return 0. Return the number ofīytes just being sent. Splice.splice(out, in, offset, nbytes, flags)Ĭopy nbytes bytes from file descriptor in (a regular file) to fileĭescriptor out (a regular file) starting at offset. Sendfile module provides a single function: sendfile(). Requiring a context switch) used internally for the data copying. System call (and thus only one context switch), rather than the series of Penalties by avoiding any use of userland buffers it also results in a single This copying of the data twice (once into the userland buffer, and once outįrom that userland buffer) imposes some performance and resource penalties. # copy data from one file to another using splice from splice import splice to_read = open ( "read.txt" ) to_write = open ( "write.txt", "w+" ) splice ( to_read. To another using the splice(2) system call. Illustrated below is a simple example of copying data from one file It essentialy transfers the data by remapping pagesĪnd not actually performing the copying of data, resulting in Zero-copy allows us to operate on data without the use of copyingĭata to userspace. To be copied is first stored in a buffer in userspace and is thenĬopied back to the target data stream from the user space which Normally when you copy data from one data stream to another, the data Of data from the file descriptor in to the file descriptor out. Aboutĭata between two file descriptors without copying between kernelĪddress space and user address space. ![]() A Python interface to splice(2) system call. ![]()
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