homework-jianmu/docs/examples/rust/nativeexample/examples/subscribe_demo.rs

92 lines
2.9 KiB
Rust

use std::time::Duration;
use chrono::{DateTime, Local};
use taos::*;
// Query options 2, use deserialization with serde.
#[derive(Debug, serde::Deserialize)]
#[allow(dead_code)]
struct Record {
// deserialize timestamp to chrono::DateTime<Local>
ts: DateTime<Local>,
// float to f32
current: Option<f32>,
// int to i32
voltage: Option<i32>,
phase: Option<f32>,
}
async fn prepare(taos: Taos) -> anyhow::Result<()> {
let inserted = taos.exec_many([
// create child table
"CREATE TABLE `d0` USING `meters` TAGS(0, 'California.LosAngles')",
// insert into child table
"INSERT INTO `d0` values(now - 10s, 10, 116, 0.32)",
// insert with NULL values
"INSERT INTO `d0` values(now - 8s, NULL, NULL, NULL)",
// insert and automatically create table with tags if not exists
"INSERT INTO `d1` USING `meters` TAGS(1, 'California.SanFrancisco') values(now - 9s, 10.1, 119, 0.33)",
// insert many records in a single sql
"INSERT INTO `d1` values (now-8s, 10, 120, 0.33) (now - 6s, 10, 119, 0.34) (now - 4s, 11.2, 118, 0.322)",
]).await?;
assert_eq!(inserted, 6);
Ok(())
}
#[tokio::main]
async fn main() -> anyhow::Result<()> {
let dsn = "taos://localhost:6030";
let builder = TaosBuilder::from_dsn(dsn)?;
let taos = builder.build()?;
let db = "tmq";
// prepare database
taos.exec_many([
format!("DROP TOPIC IF EXISTS tmq_meters"),
format!("DROP DATABASE IF EXISTS `{db}`"),
format!("CREATE DATABASE `{db}` WAL_RETENTION_PERIOD 3600"),
format!("USE `{db}`"),
// create super table
format!("CREATE TABLE `meters` (`ts` TIMESTAMP, `current` FLOAT, `voltage` INT, `phase` FLOAT) TAGS (`groupid` INT, `location` BINARY(24))"),
// create topic for subscription
format!("CREATE TOPIC tmq_meters AS SELECT * FROM `meters`")
])
.await?;
let task = tokio::spawn(prepare(taos));
tokio::time::sleep(Duration::from_secs(1)).await;
// subscribe
let tmq = TmqBuilder::from_dsn("taos://localhost:6030/?group.id=test")?;
let mut consumer = tmq.build()?;
consumer.subscribe(["tmq_meters"]).await?;
consumer
.stream()
.try_for_each(|(offset, message)| async {
let topic = offset.topic();
// the vgroup id, like partition id in kafka.
let vgroup_id = offset.vgroup_id();
println!("* in vgroup id {vgroup_id} of topic {topic}\n");
if let Some(data) = message.into_data() {
while let Some(block) = data.fetch_raw_block().await? {
let records: Vec<Record> = block.deserialize().try_collect()?;
println!("** read {} records: {:#?}\n", records.len(), records);
}
}
consumer.commit(offset).await?;
Ok(())
})
.await?;
consumer.unsubscribe().await;
task.await??;
Ok(())
}