Remove lazy-static dependency

procfs/Cargo.toml

@@ -20,7 +20,6 @@ serde1 = ["serde", "procfs-core/serde1"]
 procfs-core = { path = "../procfs-core", version = "0.16.0-RC1", default-features = false }
 rustix = { version = "0.38.19", features = ["fs", "process", "param", "system", "thread"] }
 bitflags = { version = "2.0", default-features = false }
-lazy_static = "1.0.2"
 chrono = {version = "0.4.20", optional = true, features = ["clock"], default-features = false }
 hex = "0.4"
 flate2 = { version = "1.0.3", optional = true }

procfs/src/lib.rs

@@ -49,7 +49,6 @@
 pub use procfs_core::*;
 
 use bitflags::bitflags;
-use lazy_static::lazy_static;
 
 use rustix::fd::AsFd;
 use std::collections::HashMap;
@@ -202,28 +201,6 @@ pub use crate::sys::kernel::BuildInfo as KernelBuildInfo;
 pub use crate::sys::kernel::Type as KernelType;
 pub use crate::sys::kernel::Version as KernelVersion;
 
-lazy_static! {
-    /// The number of clock ticks per second.
-    ///
-    /// This is calculated from `sysconf(_SC_CLK_TCK)`.
-    static ref TICKS_PER_SECOND: u64 = {
-        ticks_per_second()
-    };
-    /// The version of the currently running kernel.
-    ///
-    /// This is a lazily constructed static.  You can also get this information via
-    /// [KernelVersion::new()].
-    static ref KERNEL: ProcResult<KernelVersion> = {
-        KernelVersion::current()
-    };
-    /// Memory page size, in bytes.
-    ///
-    /// This is calculated from `sysconf(_SC_PAGESIZE)`.
-    static ref PAGESIZE: u64 = {
-        page_size()
-    };
-}
-
 /// A wrapper around a `File` that remembers the name of the path
 struct FileWrapper {
     inner: File,
@@ -524,9 +501,7 @@ mod tests {
 
     #[test]
     fn test_statics() {
-        println!("{:?}", *TICKS_PER_SECOND);
-        println!("{:?}", *KERNEL);
-        println!("{:?}", *PAGESIZE);
+        println!("{:?}", crate::sys::kernel::Version::cached());
     }
 
     #[test]

procfs/src/process/mod.rs

@@ -66,6 +66,7 @@
 
 use super::*;
 use crate::net::{TcpNetEntry, UdpNetEntry};
+use crate::sys::kernel::Version;
 
 pub use procfs_core::process::*;
 use rustix::fd::{AsFd, BorrowedFd, OwnedFd, RawFd};
@@ -154,7 +155,7 @@ impl FDInfo {
         let p = path.as_ref();
         let root = base.as_ref().join(p);
         // for 2.6.39 <= kernel < 3.6 fstat doesn't support O_PATH see https://github.com/eminence/procfs/issues/265
-        let flags = match *crate::KERNEL {
+        let flags = match Version::cached() {
             Ok(v) if v < KernelVersion::new(3, 6, 0) => OFlags::NOFOLLOW | OFlags::CLOEXEC,
             Ok(_) => OFlags::NOFOLLOW | OFlags::PATH | OFlags::CLOEXEC,
             Err(_) => OFlags::NOFOLLOW | OFlags::PATH | OFlags::CLOEXEC,
@@ -224,7 +225,7 @@ impl Process {
     /// Returns a `Process` based on a specified `/proc/<pid>` path.
     pub fn new_with_root(root: PathBuf) -> ProcResult<Process> {
         // for 2.6.39 <= kernel < 3.6 fstat doesn't support O_PATH see https://github.com/eminence/procfs/issues/265
-        let flags = match *crate::KERNEL {
+        let flags = match Version::cached() {
             Ok(v) if v < KernelVersion::new(3, 6, 0) => OFlags::DIRECTORY | OFlags::CLOEXEC,
             Ok(_) => OFlags::PATH | OFlags::DIRECTORY | OFlags::CLOEXEC,
             Err(_) => OFlags::PATH | OFlags::DIRECTORY | OFlags::CLOEXEC,

procfs/src/sys/kernel/mod.rs

@@ -6,10 +6,11 @@
 use std::cmp;
 use std::collections::HashSet;
 use std::str::FromStr;
+use std::sync::atomic::{AtomicU32, Ordering};
 
 use bitflags::bitflags;
 
-use crate::{read_value, write_value, ProcError, ProcResult, KERNEL};
+use crate::{read_value, write_value, ProcError, ProcResult};
 
 pub mod keys;
 pub mod random;
@@ -34,6 +35,41 @@ impl Version {
         read_value("/proc/sys/kernel/osrelease")
     }
 
+    /// Cached version of the kernel version.
+    pub(crate) fn cached() -> ProcResult<Self> {
+        const SENTINEL: u32 = 0;
+        static KERNEL: AtomicU32 = AtomicU32::new(SENTINEL);
+
+        // Try to load the kernel version.
+        let mut kernel = KERNEL.load(Ordering::Relaxed);
+
+        // If we haven't loaded the kernel version yet, try to here.
+        if kernel == SENTINEL {
+            kernel = Self::current()?.to_u32();
+
+            // Try to store it in the cache.
+            KERNEL.store(kernel, Ordering::Release);
+        }
+
+        Ok(Self::from_u32(kernel))
+    }
+
+    /// Convert kernel version to an arbitrary `u32` value.
+    fn to_u32(self) -> u32 {
+        let [lo, hi] = u16::to_ne_bytes(self.patch);
+        u32::from_ne_bytes([self.major, self.minor, lo, hi])
+    }
+
+    /// Convert kernel version from an arbitrary `u32` value.
+    fn from_u32(val: u32) -> Self {
+        let [major, minor, lo, hi] = u32::to_ne_bytes(val);
+        Self {
+            major,
+            minor,
+            patch: u16::from_ne_bytes([lo, hi])
+        }
+    }
+
     /// Parses a kernel version string, in major.minor.release syntax.
     ///
     /// Note that any extra information (stuff after a dash) is ignored.
@@ -447,7 +483,7 @@ pub fn threads_max() -> ProcResult<u32> {
 /// Since Linux 4.1, this value is bounded, and must be in the range [THREADS_MIN]..=[THREADS_MAX].
 /// This function will return an error if that is not the case.
 pub fn set_threads_max(new_limit: u32) -> ProcResult<()> {
-    if let Ok(kernel) = *KERNEL {
+    if let Ok(kernel) = Version::cached() {
         if kernel.major >= 4 && kernel.minor >= 1 && !(THREADS_MIN..=THREADS_MAX).contains(&new_limit) {
             return Err(ProcError::Other(format!(
                 "{} is outside the THREADS_MIN..=THREADS_MAX range",

procfs/src/sys/kernel/random.rs

@@ -3,16 +3,14 @@
 //! Note that some of these entries are only documented in random(4), while some are also documented under proc(5)
 
 use crate::{read_value, write_value, ProcError, ProcResult};
-use lazy_static::lazy_static;
+use std::path::Path;
 
-lazy_static! {
-    static ref RANDOM_ROOT: std::path::PathBuf = std::path::PathBuf::from("/proc/sys/kernel/random");
-}
+const RANDOM_ROOT: &str = "/proc/sys/kernel/random"; 
 
 /// This read-only file gives the available entropy, in bits. This will be a number in the range
 /// 0 to 4096
 pub fn entropy_avail() -> ProcResult<u16> {
-    read_value(RANDOM_ROOT.join("entropy_avail"))
+    read_value(Path::new(RANDOM_ROOT).join("entropy_avail"))
 }
 
 /// This file gives the size of the entropy pool
@@ -22,7 +20,7 @@ pub fn entropy_avail() -> ProcResult<u16> {
 ///
 /// See `man random(4)` for more information
 pub fn poolsize() -> ProcResult<u16> {
-    read_value(RANDOM_ROOT.join("poolsize"))
+    read_value(Path::new(RANDOM_ROOT).join("poolsize"))
 }
 
 /// This file contains the number of bits of entropy required for waking up processes that sleep waiting
@@ -33,10 +31,10 @@ pub fn poolsize() -> ProcResult<u16> {
 /// This will first attempt to read from `/proc/sys/kernel/random/read_wakeup_threshold` but it
 /// will fallback to `/proc/sys/kernel/random/write_wakeup_threshold` if the former file is not found.
 pub fn read_wakeup_threshold() -> ProcResult<u32> {
-    match read_value(RANDOM_ROOT.join("read_wakeup_threshold")) {
+    match read_value(Path::new(RANDOM_ROOT).join("read_wakeup_threshold")) {
         Ok(val) => Ok(val),
         Err(err) => match err {
-            ProcError::NotFound(_) => read_value(RANDOM_ROOT.join("write_wakeup_threshold")),
+            ProcError::NotFound(_) => read_value(Path::new(RANDOM_ROOT).join("write_wakeup_threshold")),
             err => Err(err),
         },
     }
@@ -45,17 +43,17 @@ pub fn read_wakeup_threshold() -> ProcResult<u32> {
 /// This file contains the number of bits of entropy below which we wake up processes that do a
 /// select(2) or poll(2) for write access to /dev/random. These values can be changed by writing to the file.
 pub fn write_wakeup_threshold(new_value: u32) -> ProcResult<()> {
-    write_value(RANDOM_ROOT.join("write_wakeup_threshold"), new_value)
+    write_value(Path::new(RANDOM_ROOT).join("write_wakeup_threshold"), new_value)
 }
 
 /// This read-only file randomly generates a fresh 128-bit UUID on each read
 pub fn uuid() -> ProcResult<String> {
-    read_value(RANDOM_ROOT.join("uuid"))
+    read_value(Path::new(RANDOM_ROOT).join("uuid"))
 }
 
 /// This is a read-only file containing a 128-bit UUID generated at boot
 pub fn boot_id() -> ProcResult<String> {
-    read_value(RANDOM_ROOT.join("boot_id"))
+    read_value(Path::new(RANDOM_ROOT).join("boot_id"))
 }
 
 #[cfg(test)]