[Tarantool-patches] [PATCH luajit 1/3] test: add unit tests for the write buffer

[Sergey Bronnikov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

From: Sergey Bronnikov <sergeyb@tarantool.org>

The write buffer accumulates the profilers' output and passes it
to the writer on flush. It has no unit tests, so cover writing of
the data of all kinds, flushing of a full buffer, the explicit
flush and the error reporting.

Part of tarantool/tarantool#11620
---
 test/tarantool-c-tests/unit-wbuf.test.c | 388 ++++++++++++++++++++++++
 1 file changed, 388 insertions(+)
 create mode 100644 test/tarantool-c-tests/unit-wbuf.test.c

diff --git a/test/tarantool-c-tests/unit-wbuf.test.c b/test/tarantool-c-tests/unit-wbuf.test.c
new file mode 100644
index 00000000..4bee6243
--- /dev/null
+++ b/test/tarantool-c-tests/unit-wbuf.test.c
@@ -0,0 +1,388 @@
+/*
+** Testing of the write buffer.
+**
+** The write buffer accumulates the profilers' output and passes
+** it to the writer on flush. The tests below cover writing of the
+** data of all kinds, flushing on overflow, the explicit flush and
+** the error reporting.
+*/
+
+#include <errno.h>
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "lj_wbuf.h"
+#include "test.h"
+
+/* Size of the write buffer used in the tests. */
+#define BUFFER_SIZE 10
+
+/* Size of the payload that does not fit into the write buffer. */
+#define PAYLOAD_SIZE (2 * BUFFER_SIZE + 5)
+
+/* What the writer does on flush. */
+enum writer_mode {
+	/* Report all the data as written. */
+	WMODE_OK,
+	/* Report a half of the data as written and keep the buffer. */
+	WMODE_PARTIAL,
+	/* Imitate an unrecoverable write error, e.g. ENOSPC. */
+	WMODE_FAIL,
+};
+
+/* Writer context for simulating different write outcomes. */
+struct writer_ctx {
+	/* What the writer does on flush. */
+	enum writer_mode mode;
+	/* Number of performed flushes. */
+	size_t flushes;
+	/* Number of bytes reported as written. */
+	size_t written;
+	/* Everything reported as written, in order of writing. */
+	uint8_t out[2 * PAYLOAD_SIZE];
+};
+
+static size_t test_writer(const void **buf_addr, size_t len, void *opt)
+{
+	struct writer_ctx *ctx = opt;
+	size_t n = len;
+
+	ctx->flushes++;
+	if (ctx->mode == WMODE_FAIL) {
+		errno = ENOSPC;
+		*buf_addr = NULL;
+		return 0;
+	}
+	if (ctx->mode == WMODE_PARTIAL) {
+		errno = EIO;
+		n = len / 2;
+	}
+	memcpy(ctx->out + ctx->written, *buf_addr, n);
+	ctx->written += n;
+	return n;
+}
+
+static void writer_ctx_init(struct writer_ctx *ctx, enum writer_mode mode)
+{
+	memset(ctx, 0, sizeof(*ctx));
+	ctx->mode = mode;
+}
+
+static size_t buf_len(const struct lj_wbuf *buf)
+{
+	return (size_t)(buf->pos - buf->buf);
+}
+
+static void assert_stream_stopped_with_error(const struct lj_wbuf *buf)
+{
+	assert_true(lj_wbuf_test_flag(buf, STREAM_STOP));
+	assert_true(lj_wbuf_test_flag(buf, STREAM_ERRIO));
+	assert_int_equal(lj_wbuf_errno(buf), ENOSPC);
+	assert_ptr_equal(buf->buf, NULL);
+	assert_ptr_equal(buf->pos, NULL);
+}
+
+static int test_addbyte(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	writer_ctx_init(&ctx, WMODE_OK);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	lj_wbuf_addbyte(&buf, 0x7f);
+	assert_sizet_equal(buf_len(&buf), 1);
+	assert_int_equal(mem[0], 0x7f);
+	assert_sizet_equal(ctx.flushes, 0);
+	assert_int_equal(lj_wbuf_errno(&buf), 0);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+static int test_addu64(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	writer_ctx_init(&ctx, WMODE_OK);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	/* 128 is encoded as two bytes. */
+	lj_wbuf_addu64(&buf, 128);
+	assert_sizet_equal(buf_len(&buf), 2);
+	assert_int_equal(mem[0], 0x80);
+	assert_int_equal(mem[1], 0x01);
+	assert_sizet_equal(ctx.flushes, 0);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+static int test_addn(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	writer_ctx_init(&ctx, WMODE_OK);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	lj_wbuf_addn(&buf, "xyz", 3);
+	assert_sizet_equal(buf_len(&buf), 3);
+	assert_true(memcmp(mem, "xyz", 3) == 0);
+	assert_sizet_equal(ctx.flushes, 0);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+static int test_addstring(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	writer_ctx_init(&ctx, WMODE_OK);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	/* A string is a ULEB128 length followed by the payload. */
+	lj_wbuf_addstring(&buf, "xyz");
+	assert_sizet_equal(buf_len(&buf), 4);
+	assert_int_equal(mem[0], 3);
+	assert_true(memcmp(mem + 1, "xyz", 3) == 0);
+	assert_sizet_equal(ctx.flushes, 0);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+static int test_addn_pumped_through_buffer(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	uint8_t payload[PAYLOAD_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	memset(payload, 'a', sizeof(payload));
+	writer_ctx_init(&ctx, WMODE_OK);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	/*
+	 * The payload does not fit into the buffer, so it is
+	 * pumped through it. Two full buffers are flushed, the
+	 * rest stays in the buffer.
+	 */
+	lj_wbuf_addn(&buf, payload, sizeof(payload));
+	assert_sizet_equal(ctx.flushes, 2);
+	assert_sizet_equal(ctx.written, 2 * BUFFER_SIZE);
+	assert_true(memcmp(ctx.out, payload, 2 * BUFFER_SIZE) == 0);
+	assert_sizet_equal(buf_len(&buf), PAYLOAD_SIZE - 2 * BUFFER_SIZE);
+	assert_true(memcmp(mem, payload + 2 * BUFFER_SIZE,
+			   PAYLOAD_SIZE - 2 * BUFFER_SIZE) == 0);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+static int test_flush_on_overflow(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	uint8_t payload[BUFFER_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	memset(payload, 'a', sizeof(payload));
+	writer_ctx_init(&ctx, WMODE_OK);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	/* A byte written to a full buffer is preceded by a flush. */
+	lj_wbuf_addn(&buf, payload, sizeof(payload));
+	assert_sizet_equal(buf_len(&buf), sizeof(mem));
+	lj_wbuf_addbyte(&buf, 0xaa);
+	assert_sizet_equal(ctx.flushes, 1);
+	assert_sizet_equal(ctx.written, sizeof(mem));
+	assert_sizet_equal(buf_len(&buf), 1);
+	assert_int_equal(mem[0], 0xaa);
+
+	/* The same for an ULEB128 value written to a full buffer. */
+	lj_wbuf_addn(&buf, payload, sizeof(payload) - 1);
+	assert_sizet_equal(buf_len(&buf), sizeof(mem));
+	lj_wbuf_addu64(&buf, 0);
+	assert_sizet_equal(ctx.flushes, 2);
+	assert_sizet_equal(ctx.written, 2 * sizeof(mem));
+	assert_sizet_equal(buf_len(&buf), 1);
+
+	/* And for a data block written to a full buffer. */
+	lj_wbuf_addn(&buf, payload, sizeof(payload) - 1);
+	assert_sizet_equal(buf_len(&buf), sizeof(mem));
+	lj_wbuf_addn(&buf, payload, 1);
+	assert_sizet_equal(ctx.flushes, 3);
+	assert_sizet_equal(ctx.written, 3 * sizeof(mem));
+	assert_sizet_equal(buf_len(&buf), 1);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+static int test_flush(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	writer_ctx_init(&ctx, WMODE_OK);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	lj_wbuf_addn(&buf, "xyz", 3);
+	lj_wbuf_flush(&buf);
+	assert_sizet_equal(ctx.flushes, 1);
+	assert_sizet_equal(ctx.written, 3);
+	assert_true(memcmp(ctx.out, "xyz", 3) == 0);
+	/* The buffer is empty after a successful flush. */
+	assert_sizet_equal(buf_len(&buf), 0);
+	assert_false(lj_wbuf_test_flag(&buf, STREAM_ERRIO | STREAM_STOP));
+
+	/* The buffer is usable after the flush. */
+	lj_wbuf_addbyte(&buf, 0x7f);
+	assert_sizet_equal(buf_len(&buf), 1);
+	assert_int_equal(mem[0], 0x7f);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+static int test_flush_partial_write(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	writer_ctx_init(&ctx, WMODE_PARTIAL);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	lj_wbuf_addn(&buf, "xyz", 3);
+	lj_wbuf_flush(&buf);
+	/* A partial write is reported as an error. */
+	assert_true(lj_wbuf_test_flag(&buf, STREAM_ERRIO));
+	assert_int_equal(lj_wbuf_errno(&buf), EIO);
+	/* The writer keeps the buffer, so the stream is not stopped. */
+	assert_false(lj_wbuf_test_flag(&buf, STREAM_STOP));
+	assert_ptr_equal(buf.buf, mem);
+	/* The unwritten data is dropped. */
+	assert_sizet_equal(buf_len(&buf), 0);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+static int test_flush_stopped_stream(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	writer_ctx_init(&ctx, WMODE_FAIL);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	lj_wbuf_addn(&buf, "xyz", 3);
+	lj_wbuf_flush(&buf);
+	assert_stream_stopped_with_error(&buf);
+	assert_sizet_equal(ctx.flushes, 1);
+
+	/* A stopped stream is not flushed again. */
+	lj_wbuf_flush(&buf);
+	assert_sizet_equal(ctx.flushes, 1);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+static int test_write_to_stopped_stream(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	writer_ctx_init(&ctx, WMODE_FAIL);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	lj_wbuf_addn(&buf, "xyz", 3);
+	lj_wbuf_flush(&buf);
+	assert_stream_stopped_with_error(&buf);
+
+	/* Writes to a stopped stream are ignored. */
+	lj_wbuf_addbyte(&buf, 0x7f);
+	lj_wbuf_addu64(&buf, 128);
+	lj_wbuf_addn(&buf, "xyz", 3);
+	lj_wbuf_addstring(&buf, "xyz");
+	assert_stream_stopped_with_error(&buf);
+	assert_sizet_equal(ctx.flushes, 1);
+	assert_sizet_equal(ctx.written, 0);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+static int test_terminate(void *state)
+{
+	uint8_t mem[BUFFER_SIZE];
+	struct lj_wbuf buf;
+	struct writer_ctx ctx;
+
+	UNUSED(state);
+
+	writer_ctx_init(&ctx, WMODE_OK);
+	lj_wbuf_init(&buf, test_writer, &ctx, mem, sizeof(mem));
+
+	lj_wbuf_terminate(&buf);
+	assert_true(buf.writer == NULL);
+	assert_ptr_equal(buf.ctx, NULL);
+	assert_ptr_equal(buf.buf, NULL);
+	assert_ptr_equal(buf.pos, NULL);
+	assert_sizet_equal(buf.size, 0);
+	assert_false(lj_wbuf_test_flag(&buf, STREAM_ERRIO | STREAM_STOP));
+	assert_int_equal(lj_wbuf_errno(&buf), 0);
+
+	return TEST_EXIT_SUCCESS;
+}
+
+/*
+** A writer may release the buffer and set *data to NULL on an
+** unrecoverable error (e.g. ENOSPC). The stream is stopped in
+** this case, so the write functions must not touch the released
+** buffer.
+*/
+int main(void)
+{
+	const struct test_unit tgroup[] = {
+		test_unit_def(test_addbyte),
+		test_unit_def(test_addu64),
+		test_unit_def(test_addn),
+		test_unit_def(test_addstring),
+		test_unit_def(test_addn_pumped_through_buffer),
+		test_unit_def(test_flush_on_overflow),
+		test_unit_def(test_flush),
+		test_unit_def(test_flush_partial_write),
+		test_unit_def(test_flush_stopped_stream),
+		test_unit_def(test_write_to_stopped_stream),
+		test_unit_def(test_terminate),
+	};
+	const int test_result = test_run_group(tgroup, NULL);
+
+	return test_result;
+}
-- 
2.56.0