Files
neon/libs/postgres_ffi/src/lib.rs
2025-06-25 14:45:52 +01:00

429 lines
13 KiB
Rust

#![allow(non_upper_case_globals)]
#![allow(non_camel_case_types)]
#![allow(non_snake_case)]
// bindgen creates some unsafe code with no doc comments.
#![allow(clippy::missing_safety_doc)]
// noted at 1.63 that in many cases there's u32 -> u32 transmutes in bindgen code.
#![allow(clippy::useless_transmute)]
// modules included with the postgres_ffi macro depend on the types of the specific version's
// types, and trigger a too eager lint.
#![allow(clippy::duplicate_mod)]
#![deny(clippy::undocumented_unsafe_blocks)]
use bytes::Bytes;
use utils::bin_ser::SerializeError;
use utils::lsn::{Lsn, WalSegmentSize};
pub use postgres_versioninfo::PgMajorVersion;
macro_rules! postgres_ffi {
($version:ident) => {
#[path = "."]
pub mod $version {
pub mod bindings {
// bindgen generates bindings for a lot of stuff we don't need
#![allow(dead_code)]
#![allow(unsafe_op_in_unsafe_fn)]
#![allow(clippy::undocumented_unsafe_blocks)]
#![allow(clippy::ptr_offset_with_cast)]
use serde::{Deserialize, Serialize};
include!(concat!(
env!("OUT_DIR"),
"/bindings_",
stringify!($version),
".rs"
));
include!(concat!("pg_constants_", stringify!($version), ".rs"));
}
pub mod controlfile_utils;
pub mod nonrelfile_utils;
pub mod wal_craft_test_export;
pub mod wal_generator;
pub mod waldecoder_handler;
pub mod xlog_utils;
pub const PG_MAJORVERSION: &str = stringify!($version);
// Re-export some symbols from bindings
pub use bindings::{CheckPoint, ControlFileData, DBState_DB_SHUTDOWNED, XLogRecord};
pub const ZERO_CHECKPOINT: bytes::Bytes =
bytes::Bytes::from_static(&[0u8; xlog_utils::SIZEOF_CHECKPOINT]);
}
};
}
#[macro_export]
macro_rules! for_all_postgres_versions {
($macro:tt) => {
$macro!(v14);
$macro!(v15);
$macro!(v16);
$macro!(v17);
};
}
for_all_postgres_versions! { postgres_ffi }
/// dispatch_pgversion
///
/// Run a code block in a context where the postgres_ffi bindings for a
/// specific (supported) PostgreSQL version are `use`-ed in scope under the pgv
/// identifier.
/// If the provided pg_version is not supported, we panic!(), unless the
/// optional third argument was provided (in which case that code will provide
/// the default handling instead).
///
/// Use like
///
/// dispatch_pgversion!(my_pgversion, { pgv::constants::XLOG_DBASE_CREATE })
/// dispatch_pgversion!(my_pgversion, pgv::constants::XLOG_DBASE_CREATE)
///
/// Other uses are for macro-internal purposes only and strictly unsupported.
///
#[macro_export]
macro_rules! dispatch_pgversion {
($version:expr, $code:expr) => {
dispatch_pgversion!($version, $code, panic!("Unknown PostgreSQL version {}", $version))
};
($version:expr, $code:expr, $invalid_pgver_handling:expr) => {
dispatch_pgversion!(
$version => $code,
default = $invalid_pgver_handling,
pgversions = [
$crate::PgMajorVersion::PG14 => v14,
$crate::PgMajorVersion::PG15 => v15,
$crate::PgMajorVersion::PG16 => v16,
$crate::PgMajorVersion::PG17 => v17,
]
)
};
($pgversion:expr => $code:expr,
default = $default:expr,
pgversions = [$($sv:pat => $vsv:ident),+ $(,)?]) => {
match ($pgversion.clone().into()) {
$($sv => {
use $crate::$vsv as pgv;
$code
},)+
#[allow(unreachable_patterns)]
_ => {
$default
}
}
};
}
#[macro_export]
macro_rules! enum_pgversion_dispatch {
($name:expr, $typ:ident, $bind:ident, $code:block) => {
enum_pgversion_dispatch!(
name = $name,
bind = $bind,
typ = $typ,
code = $code,
pgversions = [
V14 : v14,
V15 : v15,
V16 : v16,
V17 : v17,
]
)
};
(name = $name:expr,
bind = $bind:ident,
typ = $typ:ident,
code = $code:block,
pgversions = [$($variant:ident : $md:ident),+ $(,)?]) => {
match $name {
$(
self::$typ::$variant($bind) => {
use $crate::$md as pgv;
$code
}
),+,
}
};
}
#[macro_export]
macro_rules! enum_pgversion {
{$name:ident, pgv :: $t:ident} => {
enum_pgversion!{
name = $name,
typ = $t,
pgversions = [
V14 : v14,
V15 : v15,
V16 : v16,
V17 : v17,
]
}
};
{$name:ident, pgv :: $p:ident :: $t:ident} => {
enum_pgversion!{
name = $name,
path = $p,
typ = $t,
pgversions = [
V14 : v14,
V15 : v15,
V16 : v16,
V17 : v17,
]
}
};
{name = $name:ident,
typ = $t:ident,
pgversions = [$($variant:ident : $md:ident),+ $(,)?]} => {
pub enum $name {
$($variant ( $crate::$md::$t )),+
}
impl self::$name {
pub fn pg_version(&self) -> PgMajorVersion {
enum_pgversion_dispatch!(self, $name, _ign, {
pgv::bindings::MY_PGVERSION
})
}
}
$(
impl Into<self::$name> for $crate::$md::$t {
fn into(self) -> self::$name {
self::$name::$variant (self)
}
}
)+
};
{name = $name:ident,
path = $p:ident,
$(typ = $t:ident,)?
pgversions = [$($variant:ident : $md:ident),+ $(,)?]} => {
pub enum $name {
$($variant $(($crate::$md::$p::$t))?),+
}
impl $name {
pub fn pg_version(&self) -> PgMajorVersion {
enum_pgversion_dispatch!(self, $name, _ign, {
pgv::bindings::MY_PGVERSION
})
}
}
$(
impl Into<$name> for $crate::$md::$p::$t {
fn into(self) -> $name {
$name::$variant (self)
}
}
)+
};
}
pub mod pg_constants;
pub mod relfile_utils;
pub mod walrecord;
// Export some widely used datatypes that are unlikely to change across Postgres versions
pub use v14::bindings::{
BlockNumber, CheckPoint, ControlFileData, MultiXactId, OffsetNumber, Oid, PageHeaderData,
RepOriginId, TimeLineID, TimestampTz, TransactionId, XLogRecPtr, XLogRecord, XLogSegNo, uint32,
uint64,
};
// Likewise for these, although the assumption that these don't change is a little more iffy.
pub use v14::bindings::{MultiXactOffset, MultiXactStatus};
pub use v14::xlog_utils::{
XLOG_SIZE_OF_XLOG_LONG_PHD, XLOG_SIZE_OF_XLOG_RECORD, XLOG_SIZE_OF_XLOG_SHORT_PHD,
};
// from pg_config.h. These can be changed with configure options --with-blocksize=BLOCKSIZE and
// --with-segsize=SEGSIZE, but assume the defaults for now.
pub const BLCKSZ: u16 = 8192;
pub const RELSEG_SIZE: u32 = 1024 * 1024 * 1024 / (BLCKSZ as u32);
pub const XLOG_BLCKSZ: usize = 8192;
pub const WAL_SEGMENT_SIZE: WalSegmentSize = 16 * 1024 * 1024;
pub const MAX_SEND_SIZE: usize = XLOG_BLCKSZ * 16;
// Export some version independent functions that are used outside of this mod
pub use v14::bindings::DBState_DB_SHUTDOWNED;
pub use v14::xlog_utils::{
XLogFileName, encode_logical_message, get_current_timestamp, to_pg_timestamp,
try_from_pg_timestamp,
};
pub fn bkpimage_is_compressed(bimg_info: u8, version: PgMajorVersion) -> bool {
dispatch_pgversion!(version, pgv::bindings::bkpimg_is_compressed(bimg_info))
}
pub fn generate_wal_segment(
segno: u64,
system_id: u64,
pg_version: PgMajorVersion,
lsn: Lsn,
) -> Result<Bytes, SerializeError> {
assert_eq!(segno, lsn.segment_number(WAL_SEGMENT_SIZE));
dispatch_pgversion!(
pg_version,
pgv::xlog_utils::generate_wal_segment(segno, system_id, lsn)
)
}
pub fn generate_pg_control(
pg_control_bytes: &[u8],
checkpoint_bytes: &[u8],
lsn: Lsn,
pg_version: PgMajorVersion,
) -> anyhow::Result<(Bytes, u64, bool)> {
dispatch_pgversion!(
pg_version,
pgv::xlog_utils::generate_pg_control(pg_control_bytes, checkpoint_bytes, lsn),
anyhow::bail!("Unknown version {}", pg_version)
)
}
// PG timeline is always 1, changing it doesn't have any useful meaning in Neon.
//
// NOTE: this is not to be confused with Neon timelines; different concept!
//
// It's a shaky assumption, that it's always 1. We might import a
// PostgreSQL data directory that has gone through timeline bumps,
// for example. FIXME later.
pub const PG_TLI: u32 = 1;
// See TransactionIdIsNormal in transam.h
pub const fn transaction_id_is_normal(id: TransactionId) -> bool {
id > pg_constants::FIRST_NORMAL_TRANSACTION_ID
}
// See TransactionIdPrecedes in transam.c
pub const fn transaction_id_precedes(id1: TransactionId, id2: TransactionId) -> bool {
/*
* If either ID is a permanent XID then we can just do unsigned
* comparison. If both are normal, do a modulo-2^32 comparison.
*/
if !(transaction_id_is_normal(id1)) || !transaction_id_is_normal(id2) {
return id1 < id2;
}
let diff = id1.wrapping_sub(id2) as i32;
diff < 0
}
// Check if page is not yet initialized (port of Postgres PageIsInit() macro)
pub fn page_is_new(pg: &[u8]) -> bool {
pg[14] == 0 && pg[15] == 0 // pg_upper == 0
}
// ExtractLSN from page header
pub fn page_get_lsn(pg: &[u8]) -> Lsn {
Lsn(
((u32::from_le_bytes(pg[0..4].try_into().unwrap()) as u64) << 32)
| u32::from_le_bytes(pg[4..8].try_into().unwrap()) as u64,
)
}
pub fn page_set_lsn(pg: &mut [u8], lsn: Lsn) {
pg[0..4].copy_from_slice(&((lsn.0 >> 32) as u32).to_le_bytes());
pg[4..8].copy_from_slice(&(lsn.0 as u32).to_le_bytes());
}
// This is port of function with the same name from freespace.c.
// The only difference is that it does not have "level" parameter because XLogRecordPageWithFreeSpace
// always call it with level=FSM_BOTTOM_LEVEL
pub fn fsm_logical_to_physical(addr: BlockNumber) -> BlockNumber {
let mut leafno = addr;
const FSM_TREE_DEPTH: u32 = if pg_constants::SLOTS_PER_FSM_PAGE >= 1626 {
3
} else {
4
};
/* Count upper level nodes required to address the leaf page */
let mut pages: BlockNumber = 0;
for _l in 0..FSM_TREE_DEPTH {
pages += leafno + 1;
leafno /= pg_constants::SLOTS_PER_FSM_PAGE;
}
/* Turn the page count into 0-based block number */
pages - 1
}
pub mod waldecoder {
use std::num::NonZeroU32;
use crate::PgMajorVersion;
use bytes::{Buf, Bytes, BytesMut};
use thiserror::Error;
use utils::lsn::Lsn;
pub enum State {
WaitingForRecord,
ReassemblingRecord {
recordbuf: BytesMut,
contlen: NonZeroU32,
},
SkippingEverything {
skip_until_lsn: Lsn,
},
}
pub struct WalStreamDecoder {
pub lsn: Lsn,
pub pg_version: PgMajorVersion,
pub inputbuf: BytesMut,
pub state: State,
}
#[derive(Error, Debug, Clone)]
#[error("{msg} at {lsn}")]
pub struct WalDecodeError {
pub msg: String,
pub lsn: Lsn,
}
impl WalStreamDecoder {
pub fn new(lsn: Lsn, pg_version: PgMajorVersion) -> WalStreamDecoder {
WalStreamDecoder {
lsn,
pg_version,
inputbuf: BytesMut::new(),
state: State::WaitingForRecord,
}
}
// The latest LSN position fed to the decoder.
pub fn available(&self) -> Lsn {
self.lsn + self.inputbuf.remaining() as u64
}
/// Returns the LSN up to which the WAL decoder has processed.
///
/// If [`Self::poll_decode`] returned a record, then this will return
/// the end LSN of said record.
pub fn lsn(&self) -> Lsn {
self.lsn
}
pub fn feed_bytes(&mut self, buf: &[u8]) {
self.inputbuf.extend_from_slice(buf);
}
pub fn poll_decode(&mut self) -> Result<Option<(Lsn, Bytes)>, WalDecodeError> {
dispatch_pgversion!(
self.pg_version,
{
use pgv::waldecoder_handler::WalStreamDecoderHandler;
self.poll_decode_internal()
},
Err(WalDecodeError {
msg: format!("Unknown version {}", self.pg_version),
lsn: self.lsn,
})
)
}
}
}