First pass at Python implementation of rocket

Makefile

@@ -23,6 +23,7 @@ lint:
 test:
 ifeq ($(INSIDE_EMACS), t)
 # Use the slightly more flexible script
+	python setup.py build_ext --inplace
 	python tests/runtests.py
 else
 # Let setup.py check dependencies, build stuff, and run the test

nilmdb/server/bulkdata.py

@@ -9,19 +9,9 @@ from nilmdb.utils.printf import *
 
 import os
 import cPickle as pickle
-import struct
-import mmap
 import re
 
-# If we have the faulthandler module, use it.  All of the mmap stuff
-# might trigger a SIGSEGV or SIGBUS if we're not careful, and
-# faulthandler will give a traceback in that case.  (the Python
-# interpreter will still die either way).
-try: # pragma: no cover
-    import faulthandler
-    faulthandler.enable()
-except: # pragma: no cover
-    pass
+from . import pyrocket as rocket
 
 # Up to 256 open file descriptors at any given time.
 # These variables are global so they can be used in the decorator arguments.
@@ -83,26 +73,6 @@ class BulkData(object):
             raise ValueError("invalid path; path must contain at least one "
                              "folder")
 
-        # Get layout, and build format string for struct module
-        try:
-            layout = nilmdb.server.layout.get_named(layout_name)
-            struct_fmt = '<d'  # Little endian, double timestamp
-            struct_mapping = {
-                "int8": 'b',
-                "uint8": 'B',
-                "int16": 'h',
-                "uint16": 'H',
-                "int32": 'i',
-                "uint32": 'I',
-                "int64": 'q',
-                "uint64": 'Q',
-                "float32": 'f',
-                "float64": 'd',
-                }
-            struct_fmt += struct_mapping[layout.datatype] * layout.count
-        except KeyError:
-            raise ValueError("no such layout, or bad data types")
-
         # Create the table.  Note that we make a distinction here
         # between NilmDB paths (always Unix style, split apart
         # manually) and OS paths (built up with os.path.join)
@@ -122,11 +92,16 @@ class BulkData(object):
             raise ValueError("subdirs of this path already exist")
         os.mkdir(ospath)
 
-        # Write format string to file
-        Table.create(ospath, struct_fmt, self.file_size, self.files_per_dir)
+        try:
+            # Write format string to file
+            Table.create(ospath, layout_name, self.file_size,
+                         self.files_per_dir)
 
-        # Open and cache it
-        self.getnode(unicodepath)
+            # Open and cache it
+            self.getnode(unicodepath)
+        except:
+            os.rmdir(ospath)
+            raise
 
         # Success
         return
@@ -173,8 +148,8 @@ class BulkData(object):
 
 @nilmdb.utils.must_close(wrap_verify = False)
 class File(object):
-    """Object representing a single file on disk.  Data can be appended,
-    or the self.mmap handle can be used for random reads."""
+    """Object representing a single file on disk.  Data can be appended
+    or extracted using the rocket functions."""
 
     def __init__(self, root, subdir, filename):
         # Create path if it doesn't exist
@@ -190,46 +165,22 @@ class File(object):
         self._f.seek(0, 2)
         self.size = self._f.tell()
 
-        # Open mmap object
-        self.mmap = None
-        self._mmap_reopen()
-
-    def _mmap_reopen(self):
-        if self.size == 0:
-            # Don't mmap if the file is empty; it would fail
-            pass
-        elif self.mmap is None:
-            # Not opened yet, so open it
-            self.mmap = mmap.mmap(self._f.fileno(), 0)
-        else:
-            # Already opened, so just resize it
-            self.mmap.resize(self.size)
-
     def close(self):
-        if self.mmap is not None:
-            self.mmap.close()
         self._f.close()
 
-    def append(self, data): # pragma: no cover (below version used instead)
-        # Write data, flush it, and resize our mmap accordingly
-        self._f.write(data)
-        self._f.flush()
-        self.size += len(data)
-        self._mmap_reopen()
-
-    def append_pack_iter(self, count, packer, dataiter):
-        # An optimized verison of append, to avoid flushing the file
-        # and resizing the mmap after each data point.
+    def append_rocket_iter(self, rocket, rows, dataiter):
         try:
-            rows = []
-            for i in xrange(count):
-                row = dataiter.next()
-                rows.append(packer(*row))
-            self._f.write("".join(rows))
+            for i in xrange(rows):
+                rocket.append_list(self._f, [dataiter.next()])
         finally:
             self._f.flush()
             self.size = self._f.tell()
-            self._mmap_reopen()
+
+    def extract_rocket_list(self, rocket, offset, rows):
+        return rocket.extract_list(self._f, offset, rows)
+
+    def extract_rocket_string(self, rocket, offset, rows):
+        return rocket.extract_string(self._f, offset, rows)
 
 @nilmdb.utils.must_close(wrap_verify = False)
 class Table(object):
@@ -243,19 +194,19 @@ class Table(object):
         return os.path.isfile(os.path.join(root, "_format"))
 
     @classmethod
-    def create(cls, root, struct_fmt, file_size, files_per_dir):
-        """Initialize a table at the given OS path.
-        'struct_fmt' is a Struct module format description"""
+    def create(cls, root, layout, file_size, files_per_dir):
+        """Initialize a table at the given OS path with the
+        given layout string"""
 
         # Calculate rows per file so that each file is approximately
         # file_size bytes.
-        packer = struct.Struct(struct_fmt)
-        rows_per_file = max(file_size // packer.size, 1)
+        rkt = rocket.Rocket(layout)
+        rows_per_file = max(file_size // rkt.binary_size, 1)
 
         fmt = { "rows_per_file": rows_per_file,
                 "files_per_dir": files_per_dir,
-                "struct_fmt": struct_fmt,
-                "version": 1 }
+                "layout": layout,
+                "version": 2 }
         with open(os.path.join(root, "_format"), "wb") as f:
             pickle.dump(fmt, f, 2)
 
@@ -264,18 +215,18 @@ class Table(object):
         """'root' is the full OS path to the directory of this table"""
         self.root = root
 
-        # Load the format and build packer
+        # Load the format and build rocket
         with open(os.path.join(self.root, "_format"), "rb") as f:
             fmt = pickle.load(f)
 
-        if fmt["version"] != 1: # pragma: no cover (just future proofing)
+        if fmt["version"] != 2: # pragma: no cover (just future proofing)
             raise NotImplementedError("version " + fmt["version"] +
                                       " bulk data store not supported")
 
         self.rows_per_file = fmt["rows_per_file"]
         self.files_per_dir = fmt["files_per_dir"]
-        self.packer = struct.Struct(fmt["struct_fmt"])
-        self.file_size = self.packer.size * self.rows_per_file
+        self.rocket = rocket.Rocket(fmt["layout"])
+        self.file_size = self.rocket.binary_size * self.rows_per_file
 
         # Find nrows
         self.nrows = self._get_nrows()
@@ -330,17 +281,19 @@ class Table(object):
         # will just get longer but will still sort correctly.
         dirname = sprintf("%04x", filenum // self.files_per_dir)
         filename = sprintf("%04x", filenum % self.files_per_dir)
-        offset = (row % self.rows_per_file) * self.packer.size
+        offset = (row % self.rows_per_file) * self.rocket.binary_size
         count = self.rows_per_file - (row % self.rows_per_file)
         return (dirname, filename, offset, count)
 
     def _row_from_offset(self, subdir, filename, offset):
         """Return the row number that corresponds to the given
         'subdir/filename' and byte-offset within that file."""
-        if (offset % self.packer.size) != 0: # pragma: no cover; shouldn't occur
+        if (offset % self.rocket.binary_size) != 0: # pragma: no cover
+            # shouldn't occur, unless there is some corruption somewhere
             raise ValueError("file offset is not a multiple of data size")
         filenum = int(subdir, 16) * self.files_per_dir + int(filename, 16)
-        row = (filenum * self.rows_per_file) + (offset // self.packer.size)
+        row = ((filenum * self.rows_per_file) +
+               (offset // self.rocket.binary_size))
         return row
 
     # Cache open files
@@ -365,10 +318,33 @@ class Table(object):
             f = self.file_open(subdir, fname)
 
             # Write the data
-            f.append_pack_iter(count, self.packer.pack, dataiter)
+            f.append_rocket_iter(self.rocket, count, dataiter)
             remaining -= count
             self.nrows += count
 
+    def get_string(self, start, stop):
+        """Extract data corresponding to Python range [n:m],
+        and returns a formatted string"""
+        if (start is None or
+            stop is None or
+            start >= stop or
+            start < 0 or
+            stop > self.nrows):
+            raise IndexError("Index out of range")
+
+        ret_chunks = []
+        row = start
+        remaining = stop - start
+        while remaining:
+            (subdir, filename, offset, count) = self._offset_from_row(row)
+            if count > remaining:
+                count = remaining
+            f = self.file_open(subdir, filename)
+            ret.append(f.extract_rocket_string(self.rocket, offset, count))
+            remaining -= count
+            row += count
+        return "".join(ret)
+
     def __getitem__(self, key):
         """Extract data and return it.  Supports simple indexing
         (table[n]) and range slices (table[n:m]).  Returns a nested
@@ -392,10 +368,8 @@ class Table(object):
                 (subdir, filename, offset, count) = self._offset_from_row(row)
                 if count > remaining:
                     count = remaining
-                mm = self.file_open(subdir, filename).mmap
-                for i in xrange(count):
-                    ret.append(list(self.packer.unpack_from(mm, offset)))
-                    offset += self.packer.size
+                f = self.file_open(subdir, filename)
+                ret.extend(f.extract_rocket_list(self.rocket, offset, count))
                 remaining -= count
                 row += count
             return ret
@@ -404,9 +378,8 @@ class Table(object):
         if key < 0 or key >= self.nrows:
             raise IndexError("Index out of range")
         (subdir, filename, offset, count) = self._offset_from_row(key)
-        mm = self.file_open(subdir, filename).mmap
-        # unpack_from ignores the mmap object's current seek position
-        return list(self.packer.unpack_from(mm, offset))
+        f = self.file_open(subdir, filename)
+        return f.extract_rocket_list(self.rocket, offset, 1)[0]
 
     def _remove_rows(self, subdir, filename, start, stop):
         """Helper to mark specific rows as being removed from a
@@ -485,7 +458,7 @@ class Table(object):
             (subdir, filename, offset, count) = self._offset_from_row(row)
             if count > remaining:
                 count = remaining
-            row_offset = offset // self.packer.size
+            row_offset = offset // self.rocket.binary_size
             # Mark the rows as being removed
             self._remove_rows(subdir, filename, row_offset, row_offset + count)
             remaining -= count

nilmdb/server/pyrocket.py

@@ -0,0 +1,54 @@
+# Python implementation of the "rocket" data parsing interface
+
+import struct
+
+class Rocket(object):
+    def __init__(self, layout):
+        self.layout = layout
+
+        # For packing/unpacking into a binary file.
+        # This will change in the C version
+        (self.ltype, lcount) = layout.split('_', 2)
+        self.lcount = int(lcount)
+        try:
+            struct_fmt = '<d'  # Little endian, double timestamp
+            struct_mapping = {
+                "int8": 'b',
+                "uint8": 'B',
+                "int16": 'h',
+                "uint16": 'H',
+                "int32": 'i',
+                "uint32": 'I',
+                "int64": 'q',
+                "uint64": 'Q',
+                "float32": 'f',
+                "float64": 'd',
+                }
+            struct_fmt += struct_mapping[self.ltype] * self.lcount
+        except KeyError:
+            raise ValueError("no such layout, or bad data types")
+        self.packer = struct.Struct(struct_fmt)
+
+    @property
+    def binary_size(self):
+        """Return size of one row of data in the binary file, in bytes"""
+        return self.packer.size
+
+    def append_list(self, file, data):
+        """Append the list data to the file"""
+        for row in data:
+            file.write(self.packer.pack(*row))
+        file.flush()
+
+    def extract_list(self, file, offset, count):
+        """Extract count rows of data from the file at offset offset.
+        Return a list of lists [[row],[row],...]"""
+        ret = []
+        file.seek(offset)
+        for i in xrange(count):
+            data = file.read(self.binary_size)
+            ret.append(list(self.packer.unpack(data)))
+        return ret
+
+    def extract_string(self, rocket, offset, rows):
+        pass

tests/test_bulkdata.py

@@ -35,8 +35,6 @@ class TestBulkData(object):
             data.create("/foo", "uint16_8")
         with assert_raises(ValueError):
             data.create("foo/bar", "uint16_8")
-        with assert_raises(ValueError):
-            data.create("/foo/bar", "uint8_8")
         data.create("/foo/bar", "uint16_8")
         data.create(u"/foo/baz/quux", "float64_16")
         with assert_raises(ValueError):