neon/libs/utils/src/lib.rs

//! `utils` is intended to be a place to put code that is shared
//! between other crates in this repository.

pub mod backoff;

/// `Lsn` type implements common tasks on Log Sequence Numbers
pub mod lsn;
/// SeqWait allows waiting for a future sequence number to arrive
pub mod seqwait;

/// A simple Read-Copy-Update implementation.
pub mod simple_rcu;

/// append only ordered map implemented with a Vec
pub mod vec_map;

pub mod bin_ser;

// helper functions for creating and fsyncing
pub mod crashsafe;

// common authentication routines
pub mod auth;

// utility functions and helper traits for unified unique id generation/serialization etc.
pub mod id;
// http endpoint utils
pub mod http;

// common log initialisation routine
pub mod logging;

pub mod lock_file;
pub mod pid_file;

// Misc
pub mod accum;
pub mod shutdown;

// Utility for binding TcpListeners with proper socket options.
pub mod tcp_listener;

// Utility for putting a raw file descriptor into non-blocking mode
pub mod nonblock;

// Default signal handling
pub mod sentry_init;
pub mod signals;

pub mod fs_ext;

pub mod history_buffer;

pub mod measured_stream;

pub mod serde_percent;
pub mod serde_regex;

pub mod pageserver_feedback;

pub mod tracing_span_assert;

pub mod rate_limit;

/// Simple once-barrier and a guard which keeps barrier awaiting.
pub mod completion;

/// Reporting utilities
pub mod error;

/// This is a shortcut to embed git sha into binaries and avoid copying the same build script to all packages
///
/// we have several cases:
/// * building locally from git repo
/// * building in CI from git repo
/// * building in docker (either in CI or locally)
///
/// One thing to note is that .git is not available in docker (and it is bad to include it there).
/// When building locally, the `git_version` is used to query .git. When building on CI and docker,
/// we don't build the actual PR branch commits, but always a "phantom" would be merge commit to
/// the target branch -- the actual PR commit from which we build from is supplied as GIT_VERSION
/// environment variable.
///
/// We ended up with this compromise between phantom would be merge commits vs. pull request branch
/// heads due to old logs becoming more reliable (github could gc the phantom merge commit
/// anytime) in #4641.
///
/// To avoid running buildscript every recompilation, we use rerun-if-env-changed option.
/// So the build script will be run only when GIT_VERSION envvar has changed.
///
/// Why not to use buildscript to get git commit sha directly without procmacro from different crate?
/// Caching and workspaces complicates that. In case `utils` is not
/// recompiled due to caching then version may become outdated.
/// git_version crate handles that case by introducing a dependency on .git internals via include_bytes! macro,
/// so if we changed the index state git_version will pick that up and rerun the macro.
///
/// Note that with git_version prefix is `git:` and in case of git version from env its `git-env:`.
///
/// #############################################################################################
/// TODO this macro is not the way the library is intended to be used, see <https://github.com/neondatabase/neon/issues/1565> for details.
/// We use `cachepot` to reduce our current CI build times: <https://github.com/neondatabase/cloud/pull/1033#issuecomment-1100935036>
/// Yet, it seems to ignore the GIT_VERSION env variable, passed to Docker build, even with build.rs that contains
/// `println!("cargo:rerun-if-env-changed=GIT_VERSION");` code for cachepot cache invalidation.
/// The problem needs further investigation and regular `const` declaration instead of a macro.
#[macro_export]
macro_rules! project_git_version {
    ($const_identifier:ident) => {
        // this should try GIT_VERSION first only then git_version::git_version!
        const $const_identifier: &::core::primitive::str = {
            const __COMMIT_FROM_GIT: &::core::primitive::str = git_version::git_version! {
                prefix = "",
                fallback = "unknown",
                args = ["--abbrev=40", "--always", "--dirty=-modified"] // always use full sha
            };

            const __ARG: &[&::core::primitive::str; 2] = &match ::core::option_env!("GIT_VERSION") {
                ::core::option::Option::Some(x) => ["git-env:", x],
                ::core::option::Option::None => ["git:", __COMMIT_FROM_GIT],
            };

            $crate::__const_format::concatcp!(__ARG[0], __ARG[1])
        };
    };
}

/// Re-export for `project_git_version` macro
#[doc(hidden)]
pub use const_format as __const_format;

/// Same as `assert!`, but evaluated during compilation and gets optimized out in runtime.
#[macro_export]
macro_rules! const_assert {
    ($($args:tt)*) => {
        const _: () = assert!($($args)*);
    };
}