Add support for COPY IN

This commit adds two new Connection methods: copy_to_table() and
copy_records_to_table() that allow copying data to the specified
table either in text or, in the latter case, record form.

Closes #123.
Closes #21.

Author: elprans

asyncpg/cluster.py

@@ -15,6 +15,7 @@
 import shutil
 import socket
 import subprocess
+import sys
 import tempfile
 import textwrap
 import time
@@ -213,10 +214,15 @@ def start(self, wait=60, *, server_settings={}, **opts):
                     'pg_ctl start exited with status {:d}: {}'.format(
                         process.returncode, stderr.decode()))
         else:
+            if os.getenv('ASYNCPG_DEBUG_SERVER'):
+                stdout = sys.stdout
+            else:
+                stdout = subprocess.DEVNULL
+
             self._daemon_process = \
                 subprocess.Popen(
                     [self._postgres, '-D', self._data_dir, *extra_args],
-                    stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL,
+                    stdout=stdout, stderr=subprocess.STDOUT,
                     preexec_fn=ensure_dead_with_parent)
 
             self._daemon_pid = self._daemon_process.pid

asyncpg/connection.py

@@ -7,6 +7,7 @@
 
 import asyncio
 import collections
+import collections.abc
 import struct
 import time
 
@@ -451,6 +452,115 @@ async def copy_from_query(self, query, *args, output,
 
         return await self._copy_out(copy_stmt, output, timeout)
 
+    async def copy_to_table(self, table_name, *, source,
+                            columns=None, schema_name=None, timeout=None,
+                            format=None, oids=None, freeze=None,
+                            delimiter=None, null=None, header=None,
+                            quote=None, escape=None, force_quote=None,
+                            force_not_null=None, force_null=None,
+                            encoding=None):
+        """Copy data to the specified table.
+
+        :param str table_name:
+            The name of the table to copy data to.
+
+        :param source:
+            A :term:`path-like object <python:path-like object>`,
+            or a :term:`file-like object <python:file-like object>`, or
+            an :term:`asynchronous iterable <python:asynchronous iterable>`
+            that returns ``bytes``, or an object supporting the
+            :term:`buffer protocol <python:buffer protocol>`.
+
+        :param list columns:
+            An optional list of column names to copy.
+
+        :param str schema_name:
+            An optional schema name to qualify the table.
+
+        :param float timeout:
+            Optional timeout value in seconds.
+
+        The remaining kewyword arguments are ``COPY`` statement options,
+        see `COPY statement documentation`_ for details.
+
+        :return: The status string of the COPY command.
+
+        .. versionadded:: 0.11.0
+
+        .. _`COPY statement documentation`: https://www.postgresql.org/docs/\
+                                            current/static/sql-copy.html
+
+        """
+        tabname = utils._quote_ident(table_name)
+        if schema_name:
+            tabname = utils._quote_ident(schema_name) + '.' + tabname
+
+        if columns:
+            cols = '({})'.format(
+                ', '.join(utils._quote_ident(c) for c in columns))
+        else:
+            cols = ''
+
+        opts = self._format_copy_opts(
+            format=format, oids=oids, freeze=freeze, delimiter=delimiter,
+            null=null, header=header, quote=quote, escape=escape,
+            force_not_null=force_not_null, force_null=force_null,
+            encoding=encoding
+        )
+
+        copy_stmt = 'COPY {tab}{cols} FROM STDIN {opts}'.format(
+            tab=tabname, cols=cols, opts=opts)
+
+        return await self._copy_in(copy_stmt, source, timeout)
+
+    async def copy_records_to_table(self, table_name, *, records,
+                                    columns=None, schema_name=None,
+                                    timeout=None):
+        """Copy a list of records to the specified table using binary COPY.
+
+        :param str table_name:
+            The name of the table to copy data to.
+
+        :param records:
+            An iterable returning row tuples to copy into the table.
+
+        :param list columns:
+            An optional list of column names to copy.
+
+        :param str schema_name:
+            An optional schema name to qualify the table.
+
+        :param float timeout:
+            Optional timeout value in seconds.
+
+        :return: The status string of the COPY command.
+
+        .. versionadded:: 0.11.0
+        """
+        tabname = utils._quote_ident(table_name)
+        if schema_name:
+            tabname = utils._quote_ident(schema_name) + '.' + tabname
+
+        if columns:
+            col_list = ', '.join(utils._quote_ident(c) for c in columns)
+            cols = '({})'.format(col_list)
+        else:
+            col_list = '*'
+            cols = ''
+
+        intro_query = 'SELECT {cols} FROM {tab} LIMIT 1'.format(
+            tab=tabname, cols=col_list)
+
+        intro_ps = await self.prepare(intro_query)
+
+        opts = '(FORMAT binary)'
+
+        copy_stmt = 'COPY {tab}{cols} FROM STDIN {opts}'.format(
+            tab=tabname, cols=cols, opts=opts)
+
+        return await self._copy_in_records(
+            copy_stmt, records, intro_ps._state, timeout)
+
     def _format_copy_opts(self, *, format=None, oids=None, freeze=None,
                           delimiter=None, null=None, header=None, quote=None,
                           escape=None, force_quote=None, force_not_null=None,
@@ -519,6 +629,60 @@ async def _writer(data):
             if opened_by_us:
                 f.close()
 
+    async def _copy_in(self, copy_stmt, source, timeout):
+        try:
+            path = compat.fspath(source)
+        except TypeError:
+            # source is not a path-like object
+            path = None
+
+        f = None
+        reader = None
+        data = None
+        opened_by_us = False
+        run_in_executor = self._loop.run_in_executor
+
+        if path is not None:
+            # a path
+            f = await run_in_executor(None, open, path, 'wb')
+            opened_by_us = True
+        elif hasattr(source, 'read'):
+            # file-like
+            f = source
+        elif isinstance(source, collections.abc.AsyncIterable):
+            # assuming calling output returns an awaitable.
+            reader = source
+        else:
+            # assuming source is an instance supporting the buffer protocol.
+            data = source
+
+        if f is not None:
+            # Copying from a file-like object.
+            class _Reader:
+                @compat.aiter_compat
+                def __aiter__(self):
+                    return self
+
+                async def __anext__(self):
+                    data = await run_in_executor(None, f.read, 524288)
+                    if len(data) == 0:
+                        raise StopAsyncIteration
+                    else:
+                        return data
+
+            reader = _Reader()
+
+        try:
+            return await self._protocol.copy_in(
+                copy_stmt, reader, data, None, None, timeout)
+        finally:
+            if opened_by_us:
+                await run_in_executor(None, f.close)
+
+    async def _copy_in_records(self, copy_stmt, records, intro_stmt, timeout):
+        return await self._protocol.copy_in(
+            copy_stmt, None, None, records, intro_stmt, timeout)
+
     async def set_type_codec(self, typename, *,
                              schema='public', encoder, decoder, binary=False):
         """Set an encoder/decoder pair for the specified data type.

asyncpg/protocol/consts.pxi

@@ -11,3 +11,5 @@ DEF _BUFFER_FREELIST_SIZE = 256
 DEF _RECORD_FREELIST_SIZE = 1024
 DEF _MEMORY_FREELIST_SIZE = 1024
 DEF _MAXINT32 = 2**31 - 1
+DEF _COPY_BUFFER_SIZE = 524288
+DEF _COPY_SIGNATURE = b"PGCOPY\n\377\r\n\0"

asyncpg/protocol/coreproto.pxd

@@ -113,6 +113,8 @@ cdef class CoreProtocol:
     cdef _process__bind(self, char mtype)
     cdef _process__copy_out(self, char mtype)
     cdef _process__copy_out_data(self, char mtype)
+    cdef _process__copy_in(self, char mtype)
+    cdef _process__copy_in_data(self, char mtype)
 
     cdef _parse_msg_authentication(self)
     cdef _parse_msg_parameter_status(self)
@@ -124,6 +126,10 @@ cdef class CoreProtocol:
     cdef _parse_msg_error_response(self, is_error)
     cdef _parse_msg_command_complete(self)
 
+    cdef _write_copy_data_msg(self, object data)
+    cdef _write_copy_done_msg(self)
+    cdef _write_copy_fail_msg(self, str cause)
+
     cdef _auth_password_message_cleartext(self)
     cdef _auth_password_message_md5(self, bytes salt)
 
@@ -157,6 +163,7 @@ cdef class CoreProtocol:
     cdef _close(self, str name, bint is_portal)
     cdef _simple_query(self, str query)
     cdef _copy_out(self, str copy_stmt)
+    cdef _copy_in(self, str copy_stmt)
     cdef _terminate(self)
 
     cdef _decode_row(self, const char* buf, ssize_t buf_len)

asyncpg/protocol/coreproto.pyx

@@ -88,6 +88,12 @@ cdef class CoreProtocol:
                         state == PROTOCOL_COPY_OUT_DONE):
                     self._process__copy_out_data(mtype)
 
+                elif state == PROTOCOL_COPY_IN:
+                    self._process__copy_in(mtype)
+
+                elif state == PROTOCOL_COPY_IN_DATA:
+                    self._process__copy_in_data(mtype)
+
                 elif state == PROTOCOL_CANCELLED:
                     # discard all messages until the sync message
                     if mtype == b'E':
@@ -356,6 +362,33 @@ cdef class CoreProtocol:
             self._parse_msg_ready_for_query()
             self._push_result()
 
+    cdef _process__copy_in(self, char mtype):
+        if mtype == b'E':
+            self._parse_msg_error_response(True)
+
+        elif mtype == b'G':
+            # CopyInResponse
+            self._set_state(PROTOCOL_COPY_IN_DATA)
+            self.buffer.consume_message()
+
+        elif mtype == b'Z':
+            # ReadyForQuery
+            self._parse_msg_ready_for_query()
+            self._push_result()
+
+    cdef _process__copy_in_data(self, char mtype):
+        if mtype == b'E':
+            self._parse_msg_error_response(True)
+
+        elif mtype == b'C':
+            # CommandComplete
+            self._parse_msg_command_complete()
+
+        elif mtype == b'Z':
+            # ReadyForQuery
+            self._parse_msg_ready_for_query()
+            self._push_result()
+
     cdef _parse_msg_command_complete(self):
         cdef:
             char* cbuf
@@ -387,6 +420,42 @@ cdef class CoreProtocol:
             self._on_result()
             self.result = None
 
+    cdef _write_copy_data_msg(self, object data):
+        cdef:
+            WriteBuffer buf
+            object mview
+            Py_buffer *pybuf
+
+        mview = PyMemoryView_GetContiguous(data, cpython.PyBUF_SIMPLE, b'C')
+
+        try:
+            pybuf = PyMemoryView_GET_BUFFER(mview)
+
+            buf = WriteBuffer.new_message(b'd')
+            buf.write_cstr(<const char *>pybuf.buf, pybuf.len)
+            buf.end_message()
+        finally:
+            mview.release()
+
+        self._write(buf)
+
+    cdef _write_copy_done_msg(self):
+        cdef:
+            WriteBuffer buf
+
+        buf = WriteBuffer.new_message(b'c')
+        buf.end_message()
+        self._write(buf)
+
+    cdef _write_copy_fail_msg(self, str cause):
+        cdef:
+            WriteBuffer buf
+
+        buf = WriteBuffer.new_message(b'f')
+        buf.write_str(cause or '', self.encoding)
+        buf.end_message()
+        self._write(buf)
+
     cdef _parse_data_msgs(self):
         cdef:
             ReadBuffer buf = self.buffer
@@ -592,6 +661,10 @@ cdef class CoreProtocol:
                     new_state == PROTOCOL_COPY_OUT_DONE):
                 self.state = new_state
 
+            elif (self.state == PROTOCOL_COPY_IN and
+                    new_state == PROTOCOL_COPY_IN_DATA):
+                self.state = new_state
+
             elif self.state == PROTOCOL_FAILED:
                 raise RuntimeError(
                     'cannot switch to state {}; '
@@ -810,6 +883,17 @@ cdef class CoreProtocol:
         buf.end_message()
         self._write(buf)
 
+    cdef _copy_in(self, str copy_stmt):
+        cdef WriteBuffer buf
+
+        self._ensure_connected()
+        self._set_state(PROTOCOL_COPY_IN)
+
+        buf = WriteBuffer.new_message(b'Q')
+        buf.write_str(copy_stmt, self.encoding)
+        buf.end_message()
+        self._write(buf)
+
     cdef _terminate(self):
         cdef WriteBuffer buf
         self._ensure_connected()

asyncpg/protocol/protocol.pxd

@@ -41,6 +41,7 @@ cdef class BaseProtocol(CoreProtocol):
 
         str last_query
 
+        bint writing_paused
         bint closing
 
         readonly uint64_t queries_count
@@ -58,6 +59,7 @@ cdef class BaseProtocol(CoreProtocol):
     cdef _on_result__simple_query(self, object waiter)
     cdef _on_result__bind(self, object waiter)
     cdef _on_result__copy_out(self, object waiter)
+    cdef _on_result__copy_in(self, object waiter)
 
     cdef _handle_waiter_on_connection_lost(self, cause)