janisslsmandcodex
28826af88d
Use SQLite for persistence and generate Rust protobuf bindings at build time. Add Docker image support for containerized deployment. Co-Authored-By: codex <[email protected]>
85 lines
3.7 KiB
Protocol Buffer
85 lines
3.7 KiB
Protocol Buffer
// Copyright 2012 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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//
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// Protobuf representation of the UniquePosition class.
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// If you change or add any fields in this file, update proto_visitors.h and
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// potentially proto_enum_conversions.{h, cc}.
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syntax = "proto2";
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option go_package = "./sync_pb";
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option java_multiple_files = true;
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option java_package = "org.chromium.components.sync.protocol";
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option optimize_for = LITE_RUNTIME;
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package sync_pb;
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// A UniquePosition is a string of bytes.
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//
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// Unique positions are unique per-item, since they are guaranteed to end with a
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// fixed-length suffix that is unique per-item. The position string may not end
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// with a '\0' byte.
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//
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// Prior to the suffix is a series of arbitrary bytes of arbitrary length.
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// Items under the same parent are positioned relative to each other by a
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// lexicographic comparison of their UniquePosition values.
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message UniquePosition {
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// History:
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//
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// Unique positions were first introduced in M28. This change was rolled out
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// in such a way that it would try to maintain backwards compatibilty with
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// clients that understood only the old int64-based positions.
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//
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// At first, clients supported only the 'value' field. This version never
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// made it to stable. We later added support for the 'compressed_value'
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// field, and clients would populate either one or the other.
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//
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// In M30, we added the custom_compressed_v1 representation. This
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// representation was better than the previous implementations in almost every
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// way. However, we could not use it right away, since older clients would
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// not understand it. We decided to write both the old-style ('value' or
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// 'custom_compressed') representation and the 'custom_compressed_v1'
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// repersentations to every protobuf during the transition period. Protobufs
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// written during this transition period would be readable by clients who
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// understand at least one of the two formats.
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//
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// In M33, we dropped support for writing the backwards-compatibility fields.
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// Protobufs written by this version or later are not be intelligible by
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// clients with version M29 or older. Those clients will end up making use of
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// the old int64 position fallback mechanism.
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// The uncompressed string of bytes representing the position.
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//
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// Deprecated. See history note above.
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optional bytes value = 1 [deprecated = true];
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// The client may choose to write a compressed position to this field instead
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// of populating the 'value' above. If it chooses to use compression, the
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// 'value' field above must be empty. The position value will be compressed
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// with gzip and stored in the compressed_value field. The position's
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// uncompressed length must be specified and written to the
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// uncompressed_length field.
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//
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// Deprecated. See history note above.
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optional bytes compressed_value = 2 [deprecated = true];
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optional uint64 uncompressed_length = 3 [deprecated = true];
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// This encoding uses compression scheme designed especially for unique
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// positions. It has the property that X < Y precisely when Compressed(X) <
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// Compressed(Y), which is very useful when the most common operation is to
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// compare these positions against each other. Their values may remain
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// compressed in memory.
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//
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// The compression scheme is implemented and documented in
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// sync/core_impl/base/unique_position.cc.
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//
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// As of M30, this is the preferred encoding. Newer clients may continue to
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// populate the 'value' and 'compressed_value' fields to ensure backwards
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// compatibility, but they will always try to read from this field first.
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optional bytes custom_compressed_v1 = 4;
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}
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