test: add fast_write_example for 3.0

docs/examples/python/fast_write_example.py

+# install dependencies:
+# recommend python >= 3.8
+# pip3 install faster-fifo
+#
+
+import logging
+import math
+import sys
+import time
+import os
+from multiprocessing import Process
+from faster_fifo import Queue
+from mockdatasource import MockDataSource
+from queue import Empty
+from typing import List
+
+logging.basicConfig(stream=sys.stdout, level=logging.DEBUG, format="%(asctime)s [%(name)s] - %(message)s")
+
+READ_TASK_COUNT = 1
+WRITE_TASK_COUNT = 1
+TABLE_COUNT = 1000
+QUEUE_SIZE = 1000000
+MAX_BATCH_SIZE = 3000
+
+read_processes = []
+write_processes = []
+
+
+def get_connection():
+    """
+    If variable TDENGINE_FIRST_EP is provided then it will be used. If not, firstEP in /etc/taos/taos.cfg will be used.
+    You can also override the default username and password by supply variable TDENGINE_USER and TDENGINE_PASSWORD
+    """
+    import taos
+    firstEP = os.environ.get("TDENGINE_FIRST_EP")
+    if firstEP:
+        host, port = firstEP.split(":")
+    else:
+        host, port = None, 0
+    user = os.environ.get("TDENGINE_USER", "root")
+    password = os.environ.get("TDENGINE_PASSWORD", "taosdata")
+    return taos.connect(host=host, port=int(port), user=user, password=password)
+
+
+# ANCHOR: read
+
+def run_read_task(task_id: int, task_queues: List[Queue]):
+    table_count_per_task = TABLE_COUNT // READ_TASK_COUNT
+    data_source = MockDataSource(f"tb{task_id}", table_count_per_task)
+    try:
+        for batch in data_source:
+            for table_id, rows in batch:
+                # hash data to different queue
+                i = table_id % len(task_queues)
+                # block putting forever when the queue is full
+                task_queues[i].put_many(rows, block=True, timeout=-1)
+    except KeyboardInterrupt:
+        pass
+
+
+# ANCHOR_END: read
+
+# ANCHOR: write
+def run_write_task(task_id: int, queue: Queue):
+    from sql_writer import SQLWriter
+    log = logging.getLogger(f"WriteTask-{task_id}")
+    writer = SQLWriter(get_connection)
+    lines = None
+    try:
+        while True:
+            try:
+                # get as many as possible
+                lines = queue.get_many(block=False, max_messages_to_get=MAX_BATCH_SIZE)
+                writer.process_lines(lines)
+            except Empty:
+                time.sleep(0.01)
+    except KeyboardInterrupt:
+        pass
+    except BaseException as e:
+        log.debug(f"lines={lines}")
+        raise e
+
+
+# ANCHOR_END: write
+
+def set_global_config():
+    argc = len(sys.argv)
+    if argc > 1:
+        global READ_TASK_COUNT
+        READ_TASK_COUNT = int(sys.argv[1])
+    if argc > 2:
+        global WRITE_TASK_COUNT
+        WRITE_TASK_COUNT = int(sys.argv[2])
+    if argc > 3:
+        global TABLE_COUNT
+        TABLE_COUNT = int(sys.argv[3])
+    if argc > 4:
+        global QUEUE_SIZE
+        QUEUE_SIZE = int(sys.argv[4])
+    if argc > 5:
+        global MAX_BATCH_SIZE
+        MAX_BATCH_SIZE = int(sys.argv[5])
+
+
+# ANCHOR: monitor
+def run_monitor_process():
+    log = logging.getLogger("DataBaseMonitor")
+    conn = get_connection()
+    conn.execute("DROP DATABASE IF EXISTS test")
+    conn.execute("CREATE DATABASE test")
+    conn.execute("CREATE STABLE test.meters (ts TIMESTAMP, current FLOAT, voltage INT, phase FLOAT) "
+                 "TAGS (location BINARY(64), groupId INT)")
+
+    def get_count():
+        res = conn.query("SELECT count(*) FROM test.meters")
+        rows = res.fetch_all()
+        return rows[0][0] if rows else 0
+
+    last_count = 0
+    while True:
+        time.sleep(10)
+        count = get_count()
+        log.info(f"count={count} speed={(count - last_count) / 10}")
+        last_count = count
+
+
+# ANCHOR_END: monitor
+# ANCHOR: main
+def main():
+    set_global_config()
+    logging.info(f"READ_TASK_COUNT={READ_TASK_COUNT}, WRITE_TASK_COUNT={WRITE_TASK_COUNT}, "
+                 f"TABLE_COUNT={TABLE_COUNT}, QUEUE_SIZE={QUEUE_SIZE}, MAX_BATCH_SIZE={MAX_BATCH_SIZE}")
+
+    monitor_process = Process(target=run_monitor_process)
+    monitor_process.start()
+    time.sleep(3)  # waiting for database ready.
+
+    task_queues: List[Queue] = []
+    # create task queues
+    for i in range(WRITE_TASK_COUNT):
+        queue = Queue(max_size_bytes=QUEUE_SIZE)
+        task_queues.append(queue)
+
+    # create write processes
+    for i in range(WRITE_TASK_COUNT):
+        p = Process(target=run_write_task, args=(i, task_queues[i]))
+        p.start()
+        logging.debug(f"WriteTask-{i} started with pid {p.pid}")
+        write_processes.append(p)
+
+    # create read processes
+    for i in range(READ_TASK_COUNT):
+        queues = assign_queues(i, task_queues)
+        p = Process(target=run_read_task, args=(i, queues))
+        p.start()
+        logging.debug(f"ReadTask-{i} started with pid {p.pid}")
+        read_processes.append(p)
+
+    try:
+        monitor_process.join()
+    except KeyboardInterrupt:
+        monitor_process.terminate()
+        [p.terminate() for p in read_processes]
+        [p.terminate() for p in write_processes]
+        [q.close() for q in task_queues]
+
+
+def assign_queues(read_task_id, task_queues):
+    """
+    Compute target queues for a specific read task.
+    """
+    ratio = WRITE_TASK_COUNT / READ_TASK_COUNT
+    from_index = math.floor(read_task_id * ratio)
+    end_index = math.ceil((read_task_id + 1) * ratio)
+    return task_queues[from_index:end_index]
+
+
+if __name__ == '__main__':
+    main()
+# ANCHOR_END: main

docs/examples/python/mockdatasource.py

+import time
+
+
+class MockDataSource:
+    samples = [
+        "8.8,119,0.32,LosAngeles,0",
+        "10.7,116,0.34,SanDiego,1",
+        "9.9,111,0.33,Hollywood,2",
+        "8.9,113,0.329,Compton,3",
+        "9.4,118,0.141,San Francisco,4"
+    ]
+
+    def __init__(self, tb_name_prefix, table_count):
+        self.table_name_prefix = tb_name_prefix + "_"
+        self.table_count = table_count
+        self.max_rows = 10000000
+        self.current_ts = round(time.time() * 1000) - self.max_rows * 100
+        # [(tableId, tableName, values),]
+        self.data = self._init_data()
+
+    def _init_data(self):
+        lines = self.samples * (self.table_count // 5 + 1)
+        data = []
+        for i in range(self.table_count):
+            table_name = self.table_name_prefix + str(i)
+            data.append((i, table_name, lines[i]))  # tableId, row
+        return data
+
+    def __iter__(self):
+        self.row = 0
+        return self
+
+    def __next__(self):
+        """
+        next 1000 rows for each table.
+        return: {tableId:[row,...]}
+        """
+        # generate 1000 timestamps
+        ts = []
+        for _ in range(1000):
+            self.current_ts += 100
+            ts.append(str(self.current_ts))
+        # add timestamp to each row
+        # [(tableId, ["tableName,ts,current,voltage,phase,location,groupId"])]
+        result = []
+        for table_id, table_name, values in self.data:
+            rows = [table_name + ',' + t + ',' + values for t in ts]
+            result.append((table_id, rows))
+        return result

docs/examples/python/sql_writer.py

+import logging
+import taos
+
+
+class SQLWriter:
+    log = logging.getLogger("SQLWriter")
+
+    def __init__(self, get_connection_func):
+        self._tb_values = {}
+        self._tb_tags = {}
+        self._conn = get_connection_func()
+        self._max_sql_length = self.get_max_sql_length()
+        self._conn.execute("USE test")
+
+    def get_max_sql_length(self):
+        rows = self._conn.query("SHOW variables").fetch_all()
+        for r in rows:
+            name = r[0]
+            if name == "maxSQLLength":
+                return int(r[1])
+        return 1024 * 1024
+
+    def process_lines(self, lines: str):
+        """
+        :param lines: [[tbName,ts,current,voltage,phase,location,groupId]]
+        """
+        for line in lines:
+            ps = line.split(",")
+            table_name = ps[0]
+            value = '(' + ",".join(ps[1:-2]) + ') '
+            if table_name in self._tb_values:
+                self._tb_values[table_name] += value
+            else:
+                self._tb_values[table_name] = value
+
+            if table_name not in self._tb_tags:
+                location = ps[-2]
+                group_id = ps[-1]
+                tag_value = f"('{location}',{group_id})"
+                self._tb_tags[table_name] = tag_value
+        self.flush()
+
+    def flush(self):
+        """
+        Assemble INSERT statement and execute it.
+        When the sql length grows close to MAX_SQL_LENGTH, the sql will be executed immediately, and a new INSERT statement will be created.
+        In case of "Table does not exit" exception, tables in the sql will be created and the sql will be re-executed.
+        """
+        sql = "INSERT INTO "
+        sql_len = len(sql)
+        buf = []
+        for tb_name, values in self._tb_values.items():
+            q = tb_name + " VALUES " + values
+            if sql_len + len(q) >= self._max_sql_length:
+                sql += " ".join(buf)
+                self.execute_sql(sql)
+                sql = "INSERT INTO "
+                sql_len = len(sql)
+                buf = []
+            buf.append(q)
+            sql_len += len(q)
+        sql += " ".join(buf)
+        self.execute_sql(sql)
+        self._tb_values.clear()
+
+    def execute_sql(self, sql):
+        try:
+            self._conn.execute(sql)
+        except taos.Error as e:
+            error_code = e.errno & 0xffff
+            # Table does not exit
+            if error_code == 9731:
+                self.create_tables()
+            else:
+                self.log.error("Execute SQL: %s", sql)
+                raise e
+        except BaseException as baseException:
+            self.log.error("Execute SQL: %s", sql)
+            raise baseException
+
+    def create_tables(self):
+        sql = "CREATE TABLE "
+        for tb in self._tb_values.keys():
+            tag_values = self._tb_tags[tb]
+            sql += "IF NOT EXISTS " + tb + " USING meters TAGS " + tag_values + " "
+        try:
+            self._conn.execute(sql)
+        except BaseException as e:
+            self.log.error("Execute SQL: %s", sql)
+            raise e