Support for physical and logical replication

This patch was implemented by Petros Angelatos and Jeff Davis
to support physical and logical replication in rust-postgres
(see sfackler#752).

The original PR never made it to the upstream, but we
(Neon) still use it in our own fork of rust-postgres.

The following commits were squashed together:

* Image configuration updates.

* Make simple_query::encode() pub(crate).

* decoding logic for replication protocol

* Connection string config for replication.

* add copy_both_simple method

* helper ReplicationStream type for replication protocol

This can be optionally used with a CopyBoth stream to decode the
replication protocol

* decoding logic for logical replication protocol

* helper LogicalReplicationStream type to decode logical replication

* add postgres replication integration test

* add simple query versions of copy operations

* replication: use SystemTime for timestamps at API boundary

Co-authored-by: Petros Angelatos <petrosagg@gmail.com>
Co-authored-by: Jeff Davis <jeff@j-davis.com>

Author: 3 people

docker-compose.yml

@@ -1,6 +1,9 @@
 version: '2'
 services:
   postgres:
-    image: "sfackler/rust-postgres-test:6"
+    image: "sfackler/rust-postgres-test:7"
+    build: ./docker
+    environment:
+      - POSTGRES_PASSWORD=password
     ports:
     - 5433:5433

docker/sql_setup.sh

@@ -64,6 +64,7 @@ port = 5433
 ssl = on
 ssl_cert_file = 'server.crt'
 ssl_key_file = 'server.key'
+wal_level = logical
 EOCONF
 
 cat > "$PGDATA/pg_hba.conf" <<-EOCONF
@@ -82,6 +83,7 @@ host    all             ssl_user        ::0/0                reject
 
 # IPv4 local connections:
 host    all             postgres        0.0.0.0/0            trust
+host    replication     postgres        0.0.0.0/0            trust
 # IPv6 local connections:
 host    all             postgres        ::0/0                trust
 # Unix socket connections:

postgres-protocol/Cargo.toml

@@ -14,6 +14,7 @@ byteorder = "1.0"
 bytes = "1.0"
 fallible-iterator = "0.2"
 hmac = "0.10"
+lazy_static = "1.4"
 md-5 = "0.9"
 memchr = "2.0"
 rand = "0.8"

postgres-protocol/src/lib.rs

@@ -14,7 +14,9 @@
 
 use byteorder::{BigEndian, ByteOrder};
 use bytes::{BufMut, BytesMut};
+use lazy_static::lazy_static;
 use std::io;
+use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
 pub mod authentication;
 pub mod escape;
@@ -28,6 +30,11 @@ pub type Oid = u32;
 /// A Postgres Log Sequence Number (LSN).
 pub type Lsn = u64;
 
+lazy_static! {
+    /// Postgres epoch is 2000-01-01T00:00:00Z
+    pub static ref PG_EPOCH: SystemTime = UNIX_EPOCH + Duration::from_secs(946_684_800);
+}
+
 /// An enum indicating if a value is `NULL` or not.
 pub enum IsNull {
     /// The value is `NULL`.