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From: Stefan Reiter <s.reiter@proxmox.com>
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Date: Wed, 29 Jul 2020 14:33:12 +0200
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Subject: [pbs-devel] [PATCH proxmox-backup 3/5] tools: add nonblocking mode
to lock_file
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Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
---
src/tools.rs | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/src/tools.rs b/src/tools.rs
index 44db796d..d7b72a73 100644
--- a/src/tools.rs
+++ b/src/tools.rs
@@ -91,6 +91,9 @@ pub fn map_struct_mut<T>(buffer: &mut [u8]) -> Result<&mut T, Error> {
/// Create a file lock using fntl. This function allows you to specify
/// a timeout if you want to avoid infinite blocking.
+///
+/// With timeout set to 0, non-blocking mode is used and the function
+/// will fail immediately if the lock can't be acquired.
pub fn lock_file<F: AsRawFd>(
file: &mut F,
exclusive: bool,
@@ -110,6 +113,16 @@ pub fn lock_file<F: AsRawFd>(
Some(t) => t,
};
+ if timeout.as_nanos() == 0 {
+ let lockarg = if exclusive {
+ nix::fcntl::FlockArg::LockExclusiveNonblock
+ } else {
+ nix::fcntl::FlockArg::LockSharedNonblock
+ };
+ nix::fcntl::flock(file.as_raw_fd(), lockarg)?;
+ return Ok(());
+ }
+
// unblock the timeout signal temporarily
let _sigblock_guard = timer::unblock_timeout_signal();
--
2.20.1