ebpf: add peak() method to Queue and Stack

Signed-off-by: Xiaobo Liu <cppcoffee@gmail.com>

ebpf/aya-ebpf/src/maps/queue.rs

@@ -2,7 +2,7 @@ use core::{cell::UnsafeCell, marker::PhantomData, mem};
 
 use crate::{
     bindings::{bpf_map_def, bpf_map_type::BPF_MAP_TYPE_QUEUE},
-    helpers::{bpf_map_pop_elem, bpf_map_push_elem},
+    helpers::{bpf_map_peek_elem, bpf_map_pop_elem, bpf_map_push_elem},
     maps::PinningType,
 };
 
@@ -63,4 +63,12 @@ impl<T> Queue<T> {
             (ret == 0).then_some(value.assume_init())
         }
     }
+
+    pub fn peek(&self) -> Option<T> {
+        unsafe {
+            let mut value = mem::MaybeUninit::uninit();
+            let ret = bpf_map_peek_elem(self.def.get() as *mut _, value.as_mut_ptr() as *mut _);
+            (ret == 0).then_some(value.assume_init())
+        }
+    }
 }

ebpf/aya-ebpf/src/maps/stack.rs

@@ -2,7 +2,7 @@ use core::{marker::PhantomData, mem};
 
 use crate::{
     bindings::{bpf_map_def, bpf_map_type::BPF_MAP_TYPE_STACK},
-    helpers::{bpf_map_pop_elem, bpf_map_push_elem},
+    helpers::{bpf_map_peek_elem, bpf_map_pop_elem, bpf_map_push_elem},
     maps::PinningType,
 };
 
@@ -64,4 +64,15 @@ impl<T> Stack<T> {
             (ret == 0).then_some(value.assume_init())
         }
     }
+
+    pub fn peek(&self) -> Option<T> {
+        unsafe {
+            let mut value = mem::MaybeUninit::uninit();
+            let ret = bpf_map_peek_elem(
+                &self.def as *const _ as *mut _,
+                value.as_mut_ptr() as *mut _,
+            );
+            (ret == 0).then_some(value.assume_init())
+        }
+    }
 }

xtask/public-api/aya-ebpf.txt

@@ -438,6 +438,7 @@ pub fn aya_ebpf::maps::program_array::ProgramArray::from(t: T) -> T
 pub mod aya_ebpf::maps::queue
 #[repr(transparent)] pub struct aya_ebpf::maps::queue::Queue<T>
 impl<T> aya_ebpf::maps::queue::Queue<T>
+pub fn aya_ebpf::maps::queue::Queue<T>::peek(&self) -> core::option::Option<T>
 pub const fn aya_ebpf::maps::queue::Queue<T>::pinned(max_entries: u32, flags: u32) -> aya_ebpf::maps::queue::Queue<T>
 pub fn aya_ebpf::maps::queue::Queue<T>::pop(&self) -> core::option::Option<T>
 pub fn aya_ebpf::maps::queue::Queue<T>::push(&self, value: &T, flags: u64) -> core::result::Result<(), i64>
@@ -592,6 +593,7 @@ pub fn aya_ebpf::maps::sock_map::SockMap::from(t: T) -> T
 pub mod aya_ebpf::maps::stack
 #[repr(transparent)] pub struct aya_ebpf::maps::stack::Stack<T>
 impl<T> aya_ebpf::maps::stack::Stack<T>
+pub fn aya_ebpf::maps::stack::Stack<T>::peek(&self) -> core::option::Option<T>
 pub const fn aya_ebpf::maps::stack::Stack<T>::pinned(max_entries: u32, flags: u32) -> aya_ebpf::maps::stack::Stack<T>
 pub fn aya_ebpf::maps::stack::Stack<T>::pop(&mut self) -> core::option::Option<T>
 pub fn aya_ebpf::maps::stack::Stack<T>::push(&mut self, value: &T, flags: u64) -> core::result::Result<(), i64>
@@ -1166,6 +1168,7 @@ impl<T> core::convert::From<T> for aya_ebpf::maps::program_array::ProgramArray
 pub fn aya_ebpf::maps::program_array::ProgramArray::from(t: T) -> T
 #[repr(transparent)] pub struct aya_ebpf::maps::Queue<T>
 impl<T> aya_ebpf::maps::queue::Queue<T>
+pub fn aya_ebpf::maps::queue::Queue<T>::peek(&self) -> core::option::Option<T>
 pub const fn aya_ebpf::maps::queue::Queue<T>::pinned(max_entries: u32, flags: u32) -> aya_ebpf::maps::queue::Queue<T>
 pub fn aya_ebpf::maps::queue::Queue<T>::pop(&self) -> core::option::Option<T>
 pub fn aya_ebpf::maps::queue::Queue<T>::push(&self, value: &T, flags: u64) -> core::result::Result<(), i64>
@@ -1283,6 +1286,7 @@ impl<T> core::convert::From<T> for aya_ebpf::maps::sock_map::SockMap
 pub fn aya_ebpf::maps::sock_map::SockMap::from(t: T) -> T
 #[repr(transparent)] pub struct aya_ebpf::maps::Stack<T>
 impl<T> aya_ebpf::maps::stack::Stack<T>
+pub fn aya_ebpf::maps::stack::Stack<T>::peek(&self) -> core::option::Option<T>
 pub const fn aya_ebpf::maps::stack::Stack<T>::pinned(max_entries: u32, flags: u32) -> aya_ebpf::maps::stack::Stack<T>
 pub fn aya_ebpf::maps::stack::Stack<T>::pop(&mut self) -> core::option::Option<T>
 pub fn aya_ebpf::maps::stack::Stack<T>::push(&mut self, value: &T, flags: u64) -> core::result::Result<(), i64>