From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-3.7 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by dcvr.yhbt.net (Postfix) with ESMTP id 5CF0C1FC0B for ; Thu, 26 Nov 2020 19:44:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404687AbgKZTmm (ORCPT ); Thu, 26 Nov 2020 14:42:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404516AbgKZTmm (ORCPT ); Thu, 26 Nov 2020 14:42:42 -0500 Received: from mail-wr1-x42e.google.com (mail-wr1-x42e.google.com [IPv6:2a00:1450:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1B47BC0613D4 for ; Thu, 26 Nov 2020 11:42:42 -0800 (PST) Received: by mail-wr1-x42e.google.com with SMTP id t4so3308148wrr.12 for ; Thu, 26 Nov 2020 11:42:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=h2yM1E9OojNUlUVX9WKPZGbLmqBJ4RmwVWs00DpTaC0=; b=PknjQDqQQuMlKxz5MHJ1nwupB7hKhtx6WIGBZFwyB0nITKs9hzP0Sw/p1wRH64/8zT X3MMCxf4ezA5lqChDZt17ihCvWdoJZOscKzj9Y7V6R3Z90YWuSgtw7t7clzzJ15O7VNV QTM8WU5UjY+jOMJMokTH6UjDrbB70GbAUgo/fP+CZijskdVQTXrvR+RAZ6md+Lij4c69 PK9NjmRnjF25pAqlvcskVSnWiYndsiWA/YbCD/5CcfOs0AOOJCo10Oe/m6zk36uV3eOu huu1gj462hhXOOG9hok3LkWUrsCgZszXIGAhmUIacBkYDcFQJwBDiJM7JcwHQkpaJAvp HoVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=h2yM1E9OojNUlUVX9WKPZGbLmqBJ4RmwVWs00DpTaC0=; b=VRp9J26kgAO1AOsV9YljNXabIGZuBswul2CfDqugUw7MwkT1AkopawX1QSyryKm+ET F+nU8vfElWks6MsW4L525JRobvZ8UpRzUD/PbTygvkdOIIvrdn9AYOkoj60PABzZcmis 42ta4AN8jnH2w3X+yvbrETxtHF0bUWfhQs22Pbgcvi7J4jND1wiKdo8ZIH2eI6ewzguF FMhP7BaymoBt+VbJso+vERwdVtmwj6KQZgAWuoVpvis0yciJa5lpOx5c9S9v2yXTghjc wSTtT7FNMfaxGRFh9qAZO57nLnCV0hdZBGXk58+hY4swYrBIi6LOkbxjrYBrvYPc9IlE +AqQ== X-Gm-Message-State: AOAM531SHu+p2z6bSFibgX7r1j9chjx58pmxrezJ2OdLmgTFuI9abtKs t9kLPJ63gabWLqOn8mwO3+f9l0tN8x8= X-Google-Smtp-Source: ABdhPJzNJCDgV2Qjr7dpxQQV45HxrPbn7VI20jFZEH6/rfG8qslSOwX/yt8m544TOiynkpqHAel8hA== X-Received: by 2002:a5d:438f:: with SMTP id i15mr5857813wrq.121.1606419760341; Thu, 26 Nov 2020 11:42:40 -0800 (PST) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id l16sm10596529wrx.5.2020.11.26.11.42.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Nov 2020 11:42:39 -0800 (PST) Message-Id: In-Reply-To: References: From: "Han-Wen Nienhuys via GitGitGadget" Date: Thu, 26 Nov 2020 19:42:21 +0000 Subject: [PATCH v3 06/16] reftable: add blocksource, an abstraction for random access reads Fcc: Sent Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit MIME-Version: 1.0 To: git@vger.kernel.org Cc: Han-Wen Nienhuys , Jeff King , Ramsay Jones , Jonathan Nieder , Johannes Schindelin , Jonathan Tan , Josh Steadmon , Emily Shaffer , Patrick Steinhardt , =?UTF-8?Q?=C3=86var_Arnfj=C3=B6r=C3=B0?= Bjarmason , Han-Wen Nienhuys , Han-Wen Nienhuys Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Han-Wen Nienhuys The reftable format is usually used with files for storage. However, we abstract away this using the blocksource data structure. This has two advantages: * log blocks are zlib compressed, and handling them is simplified if we can discard byte segments from within the block layer. * for unittests, it is useful to read and write in-memory. The blocksource allows us to abstract the data away from on-disk files. Signed-off-by: Han-Wen Nienhuys --- Makefile | 1 + reftable/blocksource.c | 148 ++++++++++++++++++++++++++++++++ reftable/blocksource.h | 22 +++++ reftable/reftable-blocksource.h | 50 +++++++++++ 4 files changed, 221 insertions(+) create mode 100644 reftable/blocksource.c create mode 100644 reftable/blocksource.h create mode 100644 reftable/reftable-blocksource.h diff --git a/Makefile b/Makefile index 5ce78772fd..030b3c0204 100644 --- a/Makefile +++ b/Makefile @@ -2391,6 +2391,7 @@ XDIFF_OBJS += xdiff/xutils.o REFTABLE_OBJS += reftable/basics.o REFTABLE_OBJS += reftable/error.o +REFTABLE_OBJS += reftable/blocksource.o REFTABLE_OBJS += reftable/publicbasics.o REFTABLE_TEST_OBJS += reftable/test_framework.o diff --git a/reftable/blocksource.c b/reftable/blocksource.c new file mode 100644 index 0000000000..25d4d95b52 --- /dev/null +++ b/reftable/blocksource.c @@ -0,0 +1,148 @@ +/* +Copyright 2020 Google LLC + +Use of this source code is governed by a BSD-style +license that can be found in the LICENSE file or at +https://developers.google.com/open-source/licenses/bsd +*/ + +#include "system.h" + +#include "basics.h" +#include "blocksource.h" +#include "reftable-blocksource.h" +#include "reftable-error.h" + +static void strbuf_return_block(void *b, struct reftable_block *dest) +{ + memset(dest->data, 0xff, dest->len); + reftable_free(dest->data); +} + +static void strbuf_close(void *b) +{ +} + +static int strbuf_read_block(void *v, struct reftable_block *dest, uint64_t off, + uint32_t size) +{ + struct strbuf *b = (struct strbuf *)v; + assert(off + size <= b->len); + dest->data = reftable_calloc(size); + memcpy(dest->data, b->buf + off, size); + dest->len = size; + return size; +} + +static uint64_t strbuf_size(void *b) +{ + return ((struct strbuf *)b)->len; +} + +static struct reftable_block_source_vtable strbuf_vtable = { + .size = &strbuf_size, + .read_block = &strbuf_read_block, + .return_block = &strbuf_return_block, + .close = &strbuf_close, +}; + +void block_source_from_strbuf(struct reftable_block_source *bs, + struct strbuf *buf) +{ + assert(bs->ops == NULL); + bs->ops = &strbuf_vtable; + bs->arg = buf; +} + +static void malloc_return_block(void *b, struct reftable_block *dest) +{ + memset(dest->data, 0xff, dest->len); + reftable_free(dest->data); +} + +static struct reftable_block_source_vtable malloc_vtable = { + .return_block = &malloc_return_block, +}; + +static struct reftable_block_source malloc_block_source_instance = { + .ops = &malloc_vtable, +}; + +struct reftable_block_source malloc_block_source(void) +{ + return malloc_block_source_instance; +} + +struct file_block_source { + int fd; + uint64_t size; +}; + +static uint64_t file_size(void *b) +{ + return ((struct file_block_source *)b)->size; +} + +static void file_return_block(void *b, struct reftable_block *dest) +{ + memset(dest->data, 0xff, dest->len); + reftable_free(dest->data); +} + +static void file_close(void *b) +{ + int fd = ((struct file_block_source *)b)->fd; + if (fd > 0) { + close(fd); + ((struct file_block_source *)b)->fd = 0; + } + + reftable_free(b); +} + +static int file_read_block(void *v, struct reftable_block *dest, uint64_t off, + uint32_t size) +{ + struct file_block_source *b = (struct file_block_source *)v; + assert(off + size <= b->size); + dest->data = reftable_malloc(size); + if (pread(b->fd, dest->data, size, off) != size) + return -1; + dest->len = size; + return size; +} + +static struct reftable_block_source_vtable file_vtable = { + .size = &file_size, + .read_block = &file_read_block, + .return_block = &file_return_block, + .close = &file_close, +}; + +int reftable_block_source_from_file(struct reftable_block_source *bs, + const char *name) +{ + struct stat st = { 0 }; + int err = 0; + int fd = open(name, O_RDONLY); + struct file_block_source *p = NULL; + if (fd < 0) { + if (errno == ENOENT) { + return REFTABLE_NOT_EXIST_ERROR; + } + return -1; + } + + err = fstat(fd, &st); + if (err < 0) + return -1; + + p = reftable_calloc(sizeof(struct file_block_source)); + p->size = st.st_size; + p->fd = fd; + + assert(bs->ops == NULL); + bs->ops = &file_vtable; + bs->arg = p; + return 0; +} diff --git a/reftable/blocksource.h b/reftable/blocksource.h new file mode 100644 index 0000000000..072e2727ad --- /dev/null +++ b/reftable/blocksource.h @@ -0,0 +1,22 @@ +/* +Copyright 2020 Google LLC + +Use of this source code is governed by a BSD-style +license that can be found in the LICENSE file or at +https://developers.google.com/open-source/licenses/bsd +*/ + +#ifndef BLOCKSOURCE_H +#define BLOCKSOURCE_H + +#include "system.h" + +struct reftable_block_source; + +/* Create an in-memory block source for reading reftables */ +void block_source_from_strbuf(struct reftable_block_source *bs, + struct strbuf *buf); + +struct reftable_block_source malloc_block_source(void); + +#endif diff --git a/reftable/reftable-blocksource.h b/reftable/reftable-blocksource.h new file mode 100644 index 0000000000..fffd19deb2 --- /dev/null +++ b/reftable/reftable-blocksource.h @@ -0,0 +1,50 @@ +/* +Copyright 2020 Google LLC + +Use of this source code is governed by a BSD-style +license that can be found in the LICENSE file or at +https://developers.google.com/open-source/licenses/bsd +*/ + +#ifndef REFTABLE_BLOCKSOURCE_H +#define REFTABLE_BLOCKSOURCE_H + +#include + +/* block_source is a generic wrapper for a seekable readable file. + */ +struct reftable_block_source { + struct reftable_block_source_vtable *ops; + void *arg; +}; + +/* a contiguous segment of bytes. It keeps track of its generating block_source + so it can return itself into the pool. +*/ +struct reftable_block { + uint8_t *data; + int len; + struct reftable_block_source source; +}; + +/* block_source_vtable are the operations that make up block_source */ +struct reftable_block_source_vtable { + /* returns the size of a block source */ + uint64_t (*size)(void *source); + + /* reads a segment from the block source. It is an error to read + beyond the end of the block */ + int (*read_block)(void *source, struct reftable_block *dest, + uint64_t off, uint32_t size); + /* mark the block as read; may return the data back to malloc */ + void (*return_block)(void *source, struct reftable_block *blockp); + + /* release all resources associated with the block source */ + void (*close)(void *source); +}; + +/* opens a file on the file system as a block_source */ +int reftable_block_source_from_file(struct reftable_block_source *block_src, + const char *name); + +#endif -- gitgitgadget