admin: SHOW STATS (#46)

* admin: show stats

* warning

* tests

* lint

* type mod

.circleci/run_tests.sh

@@ -57,6 +57,10 @@ cd tests/ruby && \
     ruby tests.rb && \
 cd ../..
 
+# Admin tests
+psql -e -h 127.0.0.1 -p 6432 -d pgbouncer -c 'SHOW STATS' > /dev/null
+(! psql -e -h 127.0.0.1 -p 6432 -d random_db -c 'SHOW STATS' > /dev/null)
+
 # Start PgCat in debug to demonstrate failover better
 start_pgcat "debug"
 

src/admin.rs

@@ -0,0 +1,116 @@
+use bytes::{Buf, BufMut, BytesMut};
+use log::trace;
+use tokio::net::tcp::OwnedWriteHalf;
+
+use std::collections::HashMap;
+
+use crate::constants::{OID_NUMERIC, OID_TEXT};
+use crate::errors::Error;
+use crate::messages::write_all_half;
+use crate::stats::get_stats;
+
+/// Handle admin client
+pub async fn handle_admin(stream: &mut OwnedWriteHalf, mut query: BytesMut) -> Result<(), Error> {
+    let code = query.get_u8() as char;
+
+    if code != 'Q' {
+        return Err(Error::ProtocolSyncError);
+    }
+
+    let len = query.get_i32() as usize;
+    let query = String::from_utf8_lossy(&query[..len - 5])
+        .to_string()
+        .to_ascii_uppercase();
+
+    if query.starts_with("SHOW STATS") {
+        trace!("SHOW STATS");
+        show_stats(stream).await
+    } else {
+        Err(Error::ProtocolSyncError)
+    }
+}
+
+/// SHOW STATS
+pub async fn show_stats(stream: &mut OwnedWriteHalf) -> Result<(), Error> {
+    let columns = [
+        "database",
+        "total_xact_count",
+        "total_query_count",
+        "total_received",
+        "total_sent",
+        "total_xact_time",
+        "total_query_time",
+        "total_wait_time",
+        "avg_xact_count",
+        "avg_query_count",
+        "avg_recv",
+        "avg_sent",
+        "avg_xact_time",
+        "avg_query_time",
+        "avg_wait_time",
+    ];
+
+    let stats = get_stats().unwrap_or(HashMap::new());
+    let mut res = BytesMut::new();
+    let mut row_desc = BytesMut::new();
+    let mut data_row = BytesMut::new();
+
+    // Number of columns: 1
+    row_desc.put_i16(columns.len() as i16);
+    data_row.put_i16(columns.len() as i16);
+
+    for (i, column) in columns.iter().enumerate() {
+        // RowDescription
+
+        // Column name
+        row_desc.put_slice(&format!("{}\0", column).as_bytes());
+
+        // Doesn't belong to any table
+        row_desc.put_i32(0);
+
+        // Doesn't belong to any table
+        row_desc.put_i16(0);
+
+        // Data type
+        row_desc.put_i32(if i == 0 { OID_TEXT } else { OID_NUMERIC });
+
+        // Numeric/text size = variable (-1)
+        row_desc.put_i16(-1);
+
+        // Type modifier: none that I know
+        row_desc.put_i32(-1);
+
+        // Format being used: text (0), binary (1)
+        row_desc.put_i16(0);
+
+        // DataRow
+        let value = if i == 0 {
+            String::from("all shards")
+        } else {
+            stats.get(&column.to_string()).unwrap_or(&0).to_string()
+        };
+
+        data_row.put_i32(value.len() as i32);
+        data_row.put_slice(value.as_bytes());
+    }
+
+    let command_complete = BytesMut::from(&"SHOW\0"[..]);
+
+    res.put_u8(b'T');
+    res.put_i32(row_desc.len() as i32 + 4);
+    res.put(row_desc);
+
+    res.put_u8(b'D');
+    res.put_i32(data_row.len() as i32 + 4);
+    res.put(data_row);
+
+    res.put_u8(b'C');
+    res.put_i32(command_complete.len() as i32 + 4);
+    res.put(command_complete);
+
+    res.put_u8(b'Z');
+    res.put_i32(5);
+    res.put_u8(b'I');
+
+    write_all_half(stream, res).await
+}

src/client.rs

@@ -11,6 +11,7 @@ use tokio::net::{
 
 use std::collections::HashMap;
 
+use crate::admin::handle_admin;
 use crate::config::get_config;
 use crate::constants::*;
 use crate::errors::Error;
@@ -54,6 +55,9 @@ pub struct Client {
 
     // Statistics
     stats: Reporter,
+
+    // Clients want to talk to admin
+    admin: bool,
 }
 
 impl Client {
@@ -118,6 +122,15 @@ impl Client {
                     ready_for_query(&mut stream).await?;
                     trace!("Startup OK");
 
+                    let database = parameters
+                        .get("database")
+                        .unwrap_or(parameters.get("user").unwrap());
+                    let admin = ["pgcat", "pgbouncer"]
+                        .iter()
+                        .filter(|db| *db == &database)
+                        .count()
+                        == 1;
+
                     // Split the read and write streams
                     // so we can control buffering.
                     let (read, write) = stream.into_split();
@@ -133,6 +146,7 @@ impl Client {
                         client_server_map: client_server_map,
                         parameters: parameters,
                         stats: stats,
+                        admin: admin,
                     });
                 }
 
@@ -154,6 +168,7 @@ impl Client {
                         client_server_map: client_server_map,
                         parameters: HashMap::new(),
                         stats: stats,
+                        admin: false,
                     });
                 }
 
@@ -220,6 +235,13 @@ impl Client {
                 return Ok(());
             }
 
+            // Handle admin database real quick
+            if self.admin {
+                trace!("Handling admin command");
+                handle_admin(&mut self.write, message).await?;
+                continue;
+            }
+
             // Handle all custom protocol commands here.
             match query_router.try_execute_command(message.clone()) {
                 // Normal query

src/constants.rs

@@ -20,3 +20,9 @@ pub const AUTHENTICATION_SUCCESSFUL: i32 = 0;
 
 // ErrorResponse: A code identifying the field type; if zero, this is the message terminator and no string follows.
 pub const MESSAGE_TERMINATOR: u8 = 0;
+
+//
+// Data types
+//
+pub const OID_NUMERIC: i32 = 1700;
+pub const OID_TEXT: i32 = 25;

src/main.rs

@@ -47,6 +47,7 @@ use tokio::{
 use std::collections::HashMap;
 use std::sync::Arc;
 
+mod admin;
 mod client;
 mod config;
 mod constants;

src/messages.rs

@@ -274,7 +274,7 @@ pub async fn show_response(
     row_desc.put_i16(-1);
 
     // Type modifier: none that I know
-    row_desc.put_i32(0);
+    row_desc.put_i32(-1);
 
     // Format being used: text (0), binary (1)
     row_desc.put_i16(0);

src/stats.rs

@@ -1,12 +1,16 @@
-use log::info;
+use log::{error, info};
+use once_cell::sync::OnceCell;
 use statsd::Client;
 /// Events collector and publisher.
 use tokio::sync::mpsc::{Receiver, Sender};
 
 use std::collections::HashMap;
+use std::sync::{Arc, Mutex};
 
 use crate::config::get_config;
 
+static LATEST_STATS: OnceCell<Arc<Mutex<HashMap<String, i64>>>> = OnceCell::new();
+
 #[derive(Debug, Clone, Copy)]
 enum EventName {
     CheckoutTime,
@@ -212,6 +216,13 @@ impl Collector {
     pub async fn collect(&mut self) {
         info!("Events reporter started");
 
+        match LATEST_STATS.set(Arc::new(Mutex::new(HashMap::new()))) {
+            Ok(_) => (),
+            Err(_) => {
+                error!("Latest stats will not be available");
+            }
+        };
+
         let mut stats = HashMap::from([
             ("total_query_count", 0),
             ("total_xact_count", 0),
@@ -352,6 +363,17 @@ impl Collector {
 
                     info!("{:?}", stats);
 
+                    match LATEST_STATS.get() {
+                        Some(arc) => {
+                            let mut guard = arc.lock().unwrap();
+                            for (key, value) in &stats {
+                                guard.insert(key.to_string(), value.clone());
+                            }
+                        }
+
+                        None => (),
+                    };
+
                     let mut pipeline = self.client.pipeline();
 
                     for (key, value) in stats.iter_mut() {
@@ -365,3 +387,14 @@ impl Collector {
         }
     }
 }
+
+pub fn get_stats() -> Option<HashMap<String, i64>> {
+    match LATEST_STATS.get() {
+        Some(arc) => {
+            let guard = arc.lock().unwrap();
+            Some(guard.clone())
+        }
+
+        None => None,
+    }
+}