If your application scenario is that A writes a file and B reads it, and you are worried that A will start reading halfway through writing, you can:
1. After A finishes writing the message, he notifies B to read it again.
2.A first writes a temp file, and then renames the file to B's target file after everything is written.
If the question is about write() in POSIX, there is a way to achieve atomicity by ensuring that the data written each time does not exceed PIPE_BUF. For details, see the document of write() A note on atomicity and logic in O_NONBLOCK mode.
Atomic/non-atomic: A write is atomic if the whole amount written in one operation is not interleaved with data from any other process. ... This volume of POSIX.1-2008 ... requires that writes of { PIPE_BUF} or fewer bytes shall be atomic.
If the O_NONBLOCK flag is set ... A write request for {PIPE_BUF} or fewer bytes shall have the following effect: if there is sufficient space available in the pipe, write() shall transfer all the data and return the number of bytes requested. Otherwise, write() shall transfer no data and return -1 with errno set to [EAGAIN].
PIPE_BUF is a macro. For Linux, it is defined in <linux/limits.h>. I am not sure about other platforms.
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You need to write your own code to implement this. You can refer to the implementation method of transactions in the database
If your application scenario is that A writes a file and B reads it, and you are worried that A will start reading halfway through writing, you can:
1. After A finishes writing the message, he notifies B to read it again.
2.A first writes a temp file, and then renames the file to B's target file after everything is written.
If the question is about
write()in POSIX, there is a way to achieve atomicity by ensuring that the data written each time does not exceedPIPE_BUF. For details, see the document ofwrite()A note on atomicity and logic inO_NONBLOCKmode.PIPE_BUFis a macro. For Linux, it is defined in<linux/limits.h>. I am not sure about other platforms.