chore: add basic read write example (#10)

* add basic read write example.

* refactor by cr.

examples/read_write.py

@@ -0,0 +1,95 @@
+# Copyright 2022 CeresDB Project Authors. Licensed under Apache-2.0.
+
+import datetime
+from ceresdb_client import Builder, RpcContext, PointBuilder, ValueBuilder, WriteRequest, QueryRequest
+import asyncio
+
+
+def create_table(ctx):
+    create_table_sql = 'CREATE TABLE demo ( \
+        name string TAG, \
+        value double, \
+        t timestamp NOT NULL, \
+        TIMESTAMP KEY(t)) ENGINE=Analytic with (enable_ttl=false)'
+
+    req = QueryRequest('demo', create_table_sql)
+    _resp = sync_query(client, ctx, req)
+    print("Create table success!")
+
+
+def drop_table(ctx):
+    create_table_sql = 'DROP TABLE demo'
+
+    req = QueryRequest('demo', create_table_sql)
+    _resp = sync_query(client, ctx, req)
+    print("Drop table success!")
+
+
+async def async_query(cli, ctx, req):
+    return await cli.query(ctx, req)
+
+
+def sync_query(cli, ctx, req):
+    event_loop = asyncio.get_event_loop()
+    return event_loop.run_until_complete(async_query(cli, ctx, req))
+
+
+def process_query_resp(resp):
+    print(f"Raw resp is:\n{resp}\n")
+
+    print(f"Rows in the resp:")
+    for row_idx in range(0, resp.row_num()):
+        row_tokens = []
+        schema = resp.schema()
+        row = resp.get_row(row_idx)
+        for col_idx in range(0, schema.num_cols()):
+            name = schema.get_column_schema(col_idx).name()
+            val = row.get_column_value(col_idx)
+            row_tokens.append(f"{name}:{val}")
+        print(f"row#{col_idx}: {','.join(row_tokens)}")
+
+
+async def async_write(cli, ctx, req):
+    return await cli.write(ctx, req)
+
+
+def sync_write(cli, ctx, req):
+    event_loop = asyncio.get_event_loop()
+    return event_loop.run_until_complete(async_write(cli, ctx, req))
+
+
+def process_write_resp(resp):
+    print("success:{}, failed:{}, metrics:{}".format(resp.get_success(), resp.get_failed(), resp.get_metrics()))
+
+
+if __name__ == "__main__":
+    client = Builder("127.0.0.1:8831").build()
+    ctx = RpcContext("public", "")
+
+    print("------------------------------------------------------------------")
+    print("### create table:")
+    create_table(ctx)
+    print("------------------------------------------------------------------")
+
+    print("### write:")
+    point_builder = PointBuilder()
+    point_builder.metric('demo')
+    point_builder.timestamp(int(round(datetime.datetime.now().timestamp())))
+    point_builder.tag("name", ValueBuilder().with_str("test_tag1"))
+    point_builder.field("value", ValueBuilder().with_double(0.4242))
+    point = point_builder.build()
+    write_request = WriteRequest()
+    write_request.add_point(point)
+    resp = sync_write(client, ctx, write_request)
+    process_write_resp(resp)
+    print("------------------------------------------------------------------")
+
+    print("### read:")
+    req = QueryRequest('demo', 'select * from demo')
+    resp = sync_query(client, ctx, req)
+    process_query_resp(resp)
+    print("------------------------------------------------------------------")
+
+    print("### drop table:")
+    drop_table(ctx)
+    print("------------------------------------------------------------------")