annotate contrib/python-zstandard/c-ext/compressionchunker.c @ 40121:73fef626dae3

zstandard: vendor python-zstandard 0.10.1

This was just released.

The upstream source distribution from PyPI was extracted. Unwanted
files were removed.

The clang-format ignore list was updated to reflect the new source
of files.

setup.py was updated to pass a new argument to python-zstandard's
function for returning an Extension instance. Upstream had to change
to use relative paths because Python 3.7's packaging doesn't
seem to like absolute paths when defining sources, includes, etc.
The default relative path calculation is relative to setup_zstd.py
which is different from the directory of Mercurial's setup.py.

The project contains a vendored copy of zstandard 1.3.6. The old
version was 1.3.4.

The API should be backwards compatible and nothing in core should
need adjusted. However, there is a new "chunker" API that we
may find useful in places where we want to emit compressed chunks
of a fixed size.

There are a pair of bug fixes in 0.10.0 with regards to
compressobj() and decompressobj() when block flushing is used. I
actually found these bugs when introducing these APIs in Mercurial!
But existing Mercurial code is not affected because we don't
perform block flushing.

# no-check-commit because 3rd party code has different style guidelines

Differential Revision: https://phab.mercurial-scm.org/D4911

/**
* Copyright (c) 2018-present, Gregory Szorc
* All rights reserved.
*
* This software may be modified and distributed under the terms
* of the BSD license. See the LICENSE file for details.
*/

#include "python-zstandard.h"

extern PyObject* ZstdError;

PyDoc_STRVAR(ZstdCompressionChunkerIterator__doc__,
	"Iterator of output chunks from ZstdCompressionChunker.\n"
);

static void ZstdCompressionChunkerIterator_dealloc(ZstdCompressionChunkerIterator* self) {
	Py_XDECREF(self->chunker);

	PyObject_Del(self);
}

static PyObject* ZstdCompressionChunkerIterator_iter(PyObject* self) {
	Py_INCREF(self);
	return self;
}

static PyObject* ZstdCompressionChunkerIterator_iternext(ZstdCompressionChunkerIterator* self) {
	size_t zresult;
	PyObject* chunk;
	ZstdCompressionChunker* chunker = self->chunker;
	ZSTD_EndDirective zFlushMode;

	if (self->mode != compressionchunker_mode_normal && chunker->input.pos != chunker->input.size) {
		PyErr_SetString(ZstdError, "input should have been fully consumed before calling flush() or finish()");
		return NULL;
	}

	if (chunker->finished) {
		return NULL;
	}

	/* If we have data left in the input, consume it. */
	while (chunker->input.pos < chunker->input.size) {
		Py_BEGIN_ALLOW_THREADS
		zresult = ZSTD_compress_generic(chunker->compressor->cctx, &chunker->output,
			&chunker->input, ZSTD_e_continue);
		Py_END_ALLOW_THREADS

		/* Input is fully consumed. */
		if (chunker->input.pos == chunker->input.size) {
			chunker->input.src = NULL;
			chunker->input.pos = 0;
			chunker->input.size = 0;
			PyBuffer_Release(&chunker->inBuffer);
		}

		if (ZSTD_isError(zresult)) {
			PyErr_Format(ZstdError, "zstd compress error: %s", ZSTD_getErrorName(zresult));
			return NULL;
		}

		/* If it produced a full output chunk, emit it. */
		if (chunker->output.pos == chunker->output.size) {
			chunk = PyBytes_FromStringAndSize(chunker->output.dst, chunker->output.pos);
			if (!chunk) {
				return NULL;
			}

			chunker->output.pos = 0;

			return chunk;
		}

		/* Else continue to compress available input data. */
	}

	/* We also need this here for the special case of an empty input buffer. */
	if (chunker->input.pos == chunker->input.size) {
		chunker->input.src = NULL;
		chunker->input.pos = 0;
		chunker->input.size = 0;
		PyBuffer_Release(&chunker->inBuffer);
	}

	/* No more input data. A partial chunk may be in chunker->output.
	 * If we're in normal compression mode, we're done. Otherwise if we're in
	 * flush or finish mode, we need to emit what data remains.
	 */
	if (self->mode == compressionchunker_mode_normal) {
		/* We don't need to set StopIteration. */
		return NULL;
	}

	if (self->mode == compressionchunker_mode_flush) {
		zFlushMode = ZSTD_e_flush;
	}
	else if (self->mode == compressionchunker_mode_finish) {
		zFlushMode = ZSTD_e_end;
	}
	else {
		PyErr_SetString(ZstdError, "unhandled compression mode; this should never happen");
		return NULL;
	}

	Py_BEGIN_ALLOW_THREADS
	zresult = ZSTD_compress_generic(chunker->compressor->cctx, &chunker->output,
		&chunker->input, zFlushMode);
	Py_END_ALLOW_THREADS

	if (ZSTD_isError(zresult)) {
		PyErr_Format(ZstdError, "zstd compress error: %s",
			ZSTD_getErrorName(zresult));
		return NULL;
	}

	if (!zresult && chunker->output.pos == 0) {
		return NULL;
	}

	chunk = PyBytes_FromStringAndSize(chunker->output.dst, chunker->output.pos);
	if (!chunk) {
		return NULL;
	}

	chunker->output.pos = 0;

	if (!zresult && self->mode == compressionchunker_mode_finish) {
		chunker->finished = 1;
	}

	return chunk;
}

PyTypeObject ZstdCompressionChunkerIteratorType = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"zstd.ZstdCompressionChunkerIterator", /* tp_name */
	sizeof(ZstdCompressionChunkerIterator), /* tp_basicsize */
	0,                               /* tp_itemsize */
	(destructor)ZstdCompressionChunkerIterator_dealloc, /* tp_dealloc */
	0,                               /* tp_print */
	0,                               /* tp_getattr */
	0,                               /* tp_setattr */
	0,                               /* tp_compare */
	0,                               /* tp_repr */
	0,                               /* tp_as_number */
	0,                               /* tp_as_sequence */
	0,                               /* tp_as_mapping */
	0,                               /* tp_hash */
	0,                               /* tp_call */
	0,                               /* tp_str */
	0,                               /* tp_getattro */
	0,                               /* tp_setattro */
	0,                               /* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
	ZstdCompressionChunkerIterator__doc__, /* tp_doc */
	0,                               /* tp_traverse */
	0,                               /* tp_clear */
	0,                               /* tp_richcompare */
	0,                               /* tp_weaklistoffset */
	ZstdCompressionChunkerIterator_iter, /* tp_iter */
	(iternextfunc)ZstdCompressionChunkerIterator_iternext, /* tp_iternext */
	0,                               /* tp_methods */
	0,                               /* tp_members */
	0,                               /* tp_getset */
	0,                               /* tp_base */
	0,                               /* tp_dict */
	0,                               /* tp_descr_get */
	0,                               /* tp_descr_set */
	0,                               /* tp_dictoffset */
	0,                               /* tp_init */
	0,                               /* tp_alloc */
	PyType_GenericNew,              /* tp_new */
};

PyDoc_STRVAR(ZstdCompressionChunker__doc__,
	"Compress chunks iteratively into exact chunk sizes.\n"
);

static void ZstdCompressionChunker_dealloc(ZstdCompressionChunker* self) {
	PyBuffer_Release(&self->inBuffer);
	self->input.src = NULL;

	PyMem_Free(self->output.dst);
	self->output.dst = NULL;

	Py_XDECREF(self->compressor);

	PyObject_Del(self);
}

static ZstdCompressionChunkerIterator* ZstdCompressionChunker_compress(ZstdCompressionChunker* self, PyObject* args, PyObject* kwargs) {
	static char* kwlist[] = {
		"data",
		NULL
	};

	ZstdCompressionChunkerIterator* result;

	if (self->finished) {
		PyErr_SetString(ZstdError, "cannot call compress() after compression finished");
		return NULL;
	}

	if (self->inBuffer.obj) {
		PyErr_SetString(ZstdError,
			"cannot perform operation before consuming output from previous operation");
		return NULL;
	}

#if PY_MAJOR_VERSION >= 3
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "y*:compress",
#else
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s*:compress",
#endif
		kwlist, &self->inBuffer)) {
		return NULL;
	}

	if (!PyBuffer_IsContiguous(&self->inBuffer, 'C') || self->inBuffer.ndim > 1) {
		PyErr_SetString(PyExc_ValueError,
			"data buffer should be contiguous and have at most one dimension");
		PyBuffer_Release(&self->inBuffer);
		return NULL;
	}

	result = (ZstdCompressionChunkerIterator*)PyObject_CallObject((PyObject*)&ZstdCompressionChunkerIteratorType, NULL);
	if (!result) {
		PyBuffer_Release(&self->inBuffer);
		return NULL;
	}

	self->input.src = self->inBuffer.buf;
	self->input.size = self->inBuffer.len;
	self->input.pos = 0;

	result->chunker = self;
	Py_INCREF(result->chunker);

	result->mode = compressionchunker_mode_normal;

	return result;
}

static ZstdCompressionChunkerIterator* ZstdCompressionChunker_finish(ZstdCompressionChunker* self) {
	ZstdCompressionChunkerIterator* result;

	if (self->finished) {
		PyErr_SetString(ZstdError, "cannot call finish() after compression finished");
		return NULL;
	}

	if (self->inBuffer.obj) {
		PyErr_SetString(ZstdError,
			"cannot call finish() before consuming output from previous operation");
		return NULL;
	}

	result = (ZstdCompressionChunkerIterator*)PyObject_CallObject((PyObject*)&ZstdCompressionChunkerIteratorType, NULL);
	if (!result) {
		return NULL;
	}

	result->chunker = self;
	Py_INCREF(result->chunker);

	result->mode = compressionchunker_mode_finish;

	return result;
}

static ZstdCompressionChunkerIterator* ZstdCompressionChunker_flush(ZstdCompressionChunker* self, PyObject* args, PyObject* kwargs) {
	ZstdCompressionChunkerIterator* result;

	if (self->finished) {
		PyErr_SetString(ZstdError, "cannot call flush() after compression finished");
		return NULL;
	}

	if (self->inBuffer.obj) {
		PyErr_SetString(ZstdError,
			"cannot call flush() before consuming output from previous operation");
		return NULL;
	}

	result = (ZstdCompressionChunkerIterator*)PyObject_CallObject((PyObject*)&ZstdCompressionChunkerIteratorType, NULL);
	if (!result) {
		return NULL;
	}

	result->chunker = self;
	Py_INCREF(result->chunker);

	result->mode = compressionchunker_mode_flush;

	return result;
}

static PyMethodDef ZstdCompressionChunker_methods[] = {
	{ "compress", (PyCFunction)ZstdCompressionChunker_compress, METH_VARARGS | METH_KEYWORDS,
	PyDoc_STR("compress data") },
	{ "finish", (PyCFunction)ZstdCompressionChunker_finish, METH_NOARGS,
	PyDoc_STR("finish compression operation") },
	{ "flush", (PyCFunction)ZstdCompressionChunker_flush, METH_VARARGS | METH_KEYWORDS,
	PyDoc_STR("finish compression operation") },
	{ NULL, NULL }
};

PyTypeObject ZstdCompressionChunkerType = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"zstd.ZstdCompressionChunkerType",  /* tp_name */
	sizeof(ZstdCompressionChunker),     /* tp_basicsize */
	0,                                  /* tp_itemsize */
	(destructor)ZstdCompressionChunker_dealloc, /* tp_dealloc */
	0,                                  /* tp_print */
	0,                                  /* tp_getattr */
	0,                                  /* tp_setattr */
	0,                                  /* tp_compare */
	0,                                  /* tp_repr */
	0,                                  /* tp_as_number */
	0,                                  /* tp_as_sequence */
	0,                                  /* tp_as_mapping */
	0,                                  /* tp_hash */
	0,                                  /* tp_call */
	0,                                  /* tp_str */
	0,                                  /* tp_getattro */
	0,                                  /* tp_setattro */
	0,                                  /* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
	ZstdCompressionChunker__doc__,      /* tp_doc */
	0,                                  /* tp_traverse */
	0,                                  /* tp_clear */
	0,                                  /* tp_richcompare */
	0,                                  /* tp_weaklistoffset */
	0,                                  /* tp_iter */
	0,                                  /* tp_iternext */
	ZstdCompressionChunker_methods,     /* tp_methods */
	0,                                  /* tp_members */
	0,                                  /* tp_getset */
	0,                                  /* tp_base */
	0,                                  /* tp_dict */
	0,                                  /* tp_descr_get */
	0,                                  /* tp_descr_set */
	0,                                  /* tp_dictoffset */
	0,                                  /* tp_init */
	0,                                  /* tp_alloc */
	PyType_GenericNew,                  /* tp_new */
};

void compressionchunker_module_init(PyObject* module) {
	Py_TYPE(&ZstdCompressionChunkerIteratorType) = &PyType_Type;
	if (PyType_Ready(&ZstdCompressionChunkerIteratorType) < 0) {
		return;
	}

	Py_TYPE(&ZstdCompressionChunkerType) = &PyType_Type;
	if (PyType_Ready(&ZstdCompressionChunkerType) < 0) {
		return;
	}
}