Laszlo Ersek
2023-Apr-21 09:32 UTC
[Libguestfs] [PATCH nbdkit] rust: Add implementation of after_fork() method
On 4/21/23 11:20, Richard W.M. Jones wrote:> See: https://github.com/libguestfs/nbdkit/issues/21 > > Tested by applying the following patch to the example plugin and > running it with verbose enabled: > > --- a/plugins/rust/examples/ramdisk.rs > +++ b/plugins/rust/examples/ramdisk.rs > @@ -43,6 +43,12 @@ struct RamDisk { > } > > impl Server for RamDisk { > + fn after_fork() -> Result<()> { > + // A place to start background threads. > + eprintln!("forked"); > + Ok(()) > + } > + > fn get_size(&self) -> Result<i64> { > Ok(DISK.lock().unwrap().len() as i64) > } > @@ -76,4 +82,4 @@ impl Server for RamDisk { > } > } > > -plugin!(RamDisk {thread_model, write_at}); > +plugin!(RamDisk {thread_model, write_at, after_fork});I *think* diffs embedded in commit messages are best quoted somehow (or at least indented); I vaguely recall "naked" diffs in the commit message confusing git-am. I've not written a line of Rust thus far, so I'll let Alan review the patch. Laszlo> --- > plugins/rust/src/lib.rs | 23 ++++++++++++++++- > plugins/rust/tests/common/mod.rs | 1 + > plugins/rust/tests/full_featured.rs | 39 +++++++++++++++++++++++++++++ > 3 files changed, 62 insertions(+), 1 deletion(-) > > diff --git a/plugins/rust/src/lib.rs b/plugins/rust/src/lib.rs > index a5b88e851..fc7b28454 100644 > --- a/plugins/rust/src/lib.rs > +++ b/plugins/rust/src/lib.rs > @@ -143,6 +143,7 @@ mod unreachable { > pub(super) fn thread_model() -> Result<ThreadModel> { unreachable!() } > } > > +static mut AFTER_FORK: fn() -> Result<()> = unreachable::config_complete; > static mut CONFIG: fn(k: &str, v: &str) -> Result<()> = unreachable::config; > static mut CONFIG_COMPLETE: fn() -> Result<()> = unreachable::config_complete; > static mut CONFIG_HELP: Vec<u8> = Vec::new(); > @@ -315,6 +316,16 @@ impl ExtentHandle { > mod ffi { > use super::*; > > + pub(super) extern fn after_fork() -> c_int { > + match unsafe { AFTER_FORK() } { > + Ok(()) => 0, > + Err(e) => { > + set_error(e); > + -1 > + } > + } > + } > + > macro_rules! can_method { > ( $meth:ident ) => { > pub(super) extern fn $meth(h: *mut c_void) -> c_int { > @@ -584,6 +595,12 @@ mod ffi { > // We want the argument names to show up without underscores in the API docs > #[allow(unused_variables)] > pub trait Server { > + /// This optional callback is called before the server starts serving. > + /// > + /// It is called after the server forks and changes directory. If > + /// a plugin needs to create background threads it should do so here. > + fn after_fork() -> Result<()> where Self: Sized { unimplemented!() } > + > /// Indicates that the client intends to make further accesses to the given > /// data region. > /// > @@ -900,6 +917,7 @@ macro_rules! opt_method { > #[doc(hidden)] > #[derive(Default)] > pub struct Builder { > + pub after_fork: bool, > pub cache: bool, > pub can_cache: bool, > pub can_extents: bool, > @@ -938,6 +956,7 @@ impl Builder { > CONFIG_COMPLETE = S::config_complete; > DUMP_PLUGIN = S::dump_plugin; > GET_READY = S::get_ready; > + AFTER_FORK = S::after_fork; > LOAD = S::load; > OPEN = S::open; > PRECONNECT = S::preconnect; > @@ -1021,7 +1040,8 @@ impl Builder { > thread_model: opt_method!(self, thread_model), > can_fast_zero: opt_method!(self, can_fast_zero), > preconnect: opt_method!(self, preconnect), > - get_ready: opt_method!(self, get_ready) > + get_ready: opt_method!(self, get_ready), > + after_fork: opt_method!(self, after_fork) > }; > // Leak the memory to C. NBDKit will never give it back. > Box::into_raw(Box::new(plugin)) > @@ -1191,6 +1211,7 @@ pub struct Plugin { > pub can_fast_zero: Option<extern fn (h: *mut c_void) -> c_int>, > pub preconnect: Option<extern fn(readonly: c_int) -> c_int>, > pub get_ready: Option<extern fn() -> c_int>, > + pub after_fork: Option<extern fn() -> c_int>, > } > > /// Register your plugin with NBDKit. > diff --git a/plugins/rust/tests/common/mod.rs b/plugins/rust/tests/common/mod.rs > index de26c89fc..77c987a1f 100644 > --- a/plugins/rust/tests/common/mod.rs > +++ b/plugins/rust/tests/common/mod.rs > @@ -50,6 +50,7 @@ mock!{ > pub Server {} > #[allow(dead_code)] > impl Server for Server { > + fn after_fork() -> Result<()> where Self: Sized; > fn cache(&self, count: u32, offset: u64) -> Result<()>; > fn can_cache(&self) -> Result<CacheFlags>; > fn can_extents(&self) -> Result<bool>; > diff --git a/plugins/rust/tests/full_featured.rs b/plugins/rust/tests/full_featured.rs > index d5f02e064..87a0256e0 100644 > --- a/plugins/rust/tests/full_featured.rs > +++ b/plugins/rust/tests/full_featured.rs > @@ -46,6 +46,7 @@ static mut PLUGIN: Option<*const Plugin> = None; > static INIT: Once = Once::new(); > > plugin!(MockServer{ > + after_fork, > cache, > can_cache, > can_extents, > @@ -539,6 +540,44 @@ mod get_ready { > } > } > > +mod after_fork { > + use super::*; > + > + #[test] > + fn einval() { > + initialize(); > + let _m = MOCK_SERVER_MTX.lock().unwrap(); > + > + let after_fork_ctx = MockServer::after_fork_context(); > + after_fork_ctx.expect() > + .returning(|| Err(Error::new(libc::EINVAL, "foo is required"))); > + > + let pluginp = unsafe { PLUGIN.unwrap()}; > + let plugin = unsafe {&*pluginp}; > + > + let after_fork = plugin.after_fork.as_ref().unwrap(); > + assert_eq!( -1, after_fork()); > + ERRNO.with(|e| assert_eq!(libc::EINVAL, *e.borrow())); > + ERRMSG.with(|e| assert_eq!("foo is required", *e.borrow())); > + } > + > + #[test] > + fn ok() { > + initialize(); > + let _m = MOCK_SERVER_MTX.lock().unwrap(); > + > + let after_fork_ctx = MockServer::after_fork_context(); > + after_fork_ctx.expect() > + .returning(|| Ok(())); > + > + let pluginp = unsafe { PLUGIN.unwrap()}; > + let plugin = unsafe {&*pluginp}; > + > + let after_fork = plugin.after_fork.as_ref().unwrap(); > + assert_eq!( 0, after_fork()); > + } > +} > + > can_method!(is_rotational, expect_is_rotational); > > unload_like!(load, load_context);
Richard W.M. Jones
2023-Apr-21 10:04 UTC
[Libguestfs] [PATCH nbdkit] rust: Add implementation of after_fork() method
On Fri, Apr 21, 2023 at 11:32:31AM +0200, Laszlo Ersek wrote:> On 4/21/23 11:20, Richard W.M. Jones wrote: > > See: https://github.com/libguestfs/nbdkit/issues/21 > > > > Tested by applying the following patch to the example plugin and > > running it with verbose enabled: > > > > --- a/plugins/rust/examples/ramdisk.rs > > +++ b/plugins/rust/examples/ramdisk.rs > > @@ -43,6 +43,12 @@ struct RamDisk { > > } > > > > impl Server for RamDisk { > > + fn after_fork() -> Result<()> { > > + // A place to start background threads. > > + eprintln!("forked"); > > + Ok(()) > > + } > > + > > fn get_size(&self) -> Result<i64> { > > Ok(DISK.lock().unwrap().len() as i64) > > } > > @@ -76,4 +82,4 @@ impl Server for RamDisk { > > } > > } > > > > -plugin!(RamDisk {thread_model, write_at}); > > +plugin!(RamDisk {thread_model, write_at, after_fork}); > > I *think* diffs embedded in commit messages are best quoted somehow (or > at least indented); I vaguely recall "naked" diffs in the commit message > confusing git-am.I've now indented it in my copy. Rich.> I've not written a line of Rust thus far, so I'll let Alan review the patch. > > Laszlo > > > --- > > plugins/rust/src/lib.rs | 23 ++++++++++++++++- > > plugins/rust/tests/common/mod.rs | 1 + > > plugins/rust/tests/full_featured.rs | 39 +++++++++++++++++++++++++++++ > > 3 files changed, 62 insertions(+), 1 deletion(-) > > > > diff --git a/plugins/rust/src/lib.rs b/plugins/rust/src/lib.rs > > index a5b88e851..fc7b28454 100644 > > --- a/plugins/rust/src/lib.rs > > +++ b/plugins/rust/src/lib.rs > > @@ -143,6 +143,7 @@ mod unreachable { > > pub(super) fn thread_model() -> Result<ThreadModel> { unreachable!() } > > } > > > > +static mut AFTER_FORK: fn() -> Result<()> = unreachable::config_complete; > > static mut CONFIG: fn(k: &str, v: &str) -> Result<()> = unreachable::config; > > static mut CONFIG_COMPLETE: fn() -> Result<()> = unreachable::config_complete; > > static mut CONFIG_HELP: Vec<u8> = Vec::new(); > > @@ -315,6 +316,16 @@ impl ExtentHandle { > > mod ffi { > > use super::*; > > > > + pub(super) extern fn after_fork() -> c_int { > > + match unsafe { AFTER_FORK() } { > > + Ok(()) => 0, > > + Err(e) => { > > + set_error(e); > > + -1 > > + } > > + } > > + } > > + > > macro_rules! can_method { > > ( $meth:ident ) => { > > pub(super) extern fn $meth(h: *mut c_void) -> c_int { > > @@ -584,6 +595,12 @@ mod ffi { > > // We want the argument names to show up without underscores in the API docs > > #[allow(unused_variables)] > > pub trait Server { > > + /// This optional callback is called before the server starts serving. > > + /// > > + /// It is called after the server forks and changes directory. If > > + /// a plugin needs to create background threads it should do so here. > > + fn after_fork() -> Result<()> where Self: Sized { unimplemented!() } > > + > > /// Indicates that the client intends to make further accesses to the given > > /// data region. > > /// > > @@ -900,6 +917,7 @@ macro_rules! opt_method { > > #[doc(hidden)] > > #[derive(Default)] > > pub struct Builder { > > + pub after_fork: bool, > > pub cache: bool, > > pub can_cache: bool, > > pub can_extents: bool, > > @@ -938,6 +956,7 @@ impl Builder { > > CONFIG_COMPLETE = S::config_complete; > > DUMP_PLUGIN = S::dump_plugin; > > GET_READY = S::get_ready; > > + AFTER_FORK = S::after_fork; > > LOAD = S::load; > > OPEN = S::open; > > PRECONNECT = S::preconnect; > > @@ -1021,7 +1040,8 @@ impl Builder { > > thread_model: opt_method!(self, thread_model), > > can_fast_zero: opt_method!(self, can_fast_zero), > > preconnect: opt_method!(self, preconnect), > > - get_ready: opt_method!(self, get_ready) > > + get_ready: opt_method!(self, get_ready), > > + after_fork: opt_method!(self, after_fork) > > }; > > // Leak the memory to C. NBDKit will never give it back. > > Box::into_raw(Box::new(plugin)) > > @@ -1191,6 +1211,7 @@ pub struct Plugin { > > pub can_fast_zero: Option<extern fn (h: *mut c_void) -> c_int>, > > pub preconnect: Option<extern fn(readonly: c_int) -> c_int>, > > pub get_ready: Option<extern fn() -> c_int>, > > + pub after_fork: Option<extern fn() -> c_int>, > > } > > > > /// Register your plugin with NBDKit. > > diff --git a/plugins/rust/tests/common/mod.rs b/plugins/rust/tests/common/mod.rs > > index de26c89fc..77c987a1f 100644 > > --- a/plugins/rust/tests/common/mod.rs > > +++ b/plugins/rust/tests/common/mod.rs > > @@ -50,6 +50,7 @@ mock!{ > > pub Server {} > > #[allow(dead_code)] > > impl Server for Server { > > + fn after_fork() -> Result<()> where Self: Sized; > > fn cache(&self, count: u32, offset: u64) -> Result<()>; > > fn can_cache(&self) -> Result<CacheFlags>; > > fn can_extents(&self) -> Result<bool>; > > diff --git a/plugins/rust/tests/full_featured.rs b/plugins/rust/tests/full_featured.rs > > index d5f02e064..87a0256e0 100644 > > --- a/plugins/rust/tests/full_featured.rs > > +++ b/plugins/rust/tests/full_featured.rs > > @@ -46,6 +46,7 @@ static mut PLUGIN: Option<*const Plugin> = None; > > static INIT: Once = Once::new(); > > > > plugin!(MockServer{ > > + after_fork, > > cache, > > can_cache, > > can_extents, > > @@ -539,6 +540,44 @@ mod get_ready { > > } > > } > > > > +mod after_fork { > > + use super::*; > > + > > + #[test] > > + fn einval() { > > + initialize(); > > + let _m = MOCK_SERVER_MTX.lock().unwrap(); > > + > > + let after_fork_ctx = MockServer::after_fork_context(); > > + after_fork_ctx.expect() > > + .returning(|| Err(Error::new(libc::EINVAL, "foo is required"))); > > + > > + let pluginp = unsafe { PLUGIN.unwrap()}; > > + let plugin = unsafe {&*pluginp}; > > + > > + let after_fork = plugin.after_fork.as_ref().unwrap(); > > + assert_eq!( -1, after_fork()); > > + ERRNO.with(|e| assert_eq!(libc::EINVAL, *e.borrow())); > > + ERRMSG.with(|e| assert_eq!("foo is required", *e.borrow())); > > + } > > + > > + #[test] > > + fn ok() { > > + initialize(); > > + let _m = MOCK_SERVER_MTX.lock().unwrap(); > > + > > + let after_fork_ctx = MockServer::after_fork_context(); > > + after_fork_ctx.expect() > > + .returning(|| Ok(())); > > + > > + let pluginp = unsafe { PLUGIN.unwrap()}; > > + let plugin = unsafe {&*pluginp}; > > + > > + let after_fork = plugin.after_fork.as_ref().unwrap(); > > + assert_eq!( 0, after_fork()); > > + } > > +} > > + > > can_method!(is_rotational, expect_is_rotational); > > > > unload_like!(load, load_context);-- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com nbdkit - Flexible, fast NBD server with plugins https://gitlab.com/nbdkit/nbdkit
alan somers
2023-Apr-21 13:30 UTC
[Libguestfs] [PATCH nbdkit] rust: Add implementation of after_fork() method
On Fri, Apr 21, 2023 at 2:32?AM Laszlo Ersek <lersek at redhat.com> wrote:> > On 4/21/23 11:20, Richard W.M. Jones wrote: > > See: https://github.com/libguestfs/nbdkit/issues/21 > > > > Tested by applying the following patch to the example plugin and > > running it with verbose enabled: > > > > --- a/plugins/rust/examples/ramdisk.rs > > +++ b/plugins/rust/examples/ramdisk.rs > > @@ -43,6 +43,12 @@ struct RamDisk { > > } > > > > impl Server for RamDisk { > > + fn after_fork() -> Result<()> { > > + // A place to start background threads. > > + eprintln!("forked"); > > + Ok(()) > > + } > > + > > fn get_size(&self) -> Result<i64> { > > Ok(DISK.lock().unwrap().len() as i64) > > } > > @@ -76,4 +82,4 @@ impl Server for RamDisk { > > } > > } > > > > -plugin!(RamDisk {thread_model, write_at}); > > +plugin!(RamDisk {thread_model, write_at, after_fork}); > > I *think* diffs embedded in commit messages are best quoted somehow (or > at least indented); I vaguely recall "naked" diffs in the commit message > confusing git-am. > > I've not written a line of Rust thus far, so I'll let Alan review the patch.That patch looks good from first glance. Have you tried running it yet?