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+ // Copyright 2023 Google LLC
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+ //
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+ // Licensed under the Apache License, Version 2.0 (the "License");
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+ // you may not use this file except in compliance with the License.
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+ // You may obtain a copy of the License at
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+ //
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+ // http://www.apache.org/licenses/LICENSE-2.0
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+ //
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+ // Unless required by applicable law or agreed to in writing, software
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+ // distributed under the License is distributed on an "AS IS" BASIS,
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+ // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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+ // See the License for the specific language governing permissions and
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+ // limitations under the License.
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+
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+ syntax = "proto3" ;
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+
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+ package google.firestore.v1 ;
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+
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+ option csharp_namespace = "Google.Cloud.Firestore.V1" ;
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+ option go_package = "google.golang.org/genproto/googleapis/firestore/v1;firestore" ;
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+ option java_multiple_files = true ;
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+ option java_outer_classname = "BloomFilterProto" ;
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+ option java_package = "com.google.firestore.v1" ;
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+ option objc_class_prefix = "GCFS" ;
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+ option php_namespace = "Google\\Cloud\\Firestore\\V1" ;
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+ option ruby_package = "Google::Cloud::Firestore::V1" ;
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+
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+ // A sequence of bits, encoded in a byte array.
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+ //
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+ // Each byte in the `bitmap` byte array stores 8 bits of the sequence. The only
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+ // exception is the last byte, which may store 8 _or fewer_ bits. The `padding`
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+ // defines the number of bits of the last byte to be ignored as "padding". The
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+ // values of these "padding" bits are unspecified and must be ignored.
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+ //
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+ // To retrieve the first bit, bit 0, calculate: (bitmap[0] & 0x01) != 0.
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+ // To retrieve the second bit, bit 1, calculate: (bitmap[0] & 0x02) != 0.
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+ // To retrieve the third bit, bit 2, calculate: (bitmap[0] & 0x04) != 0.
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+ // To retrieve the fourth bit, bit 3, calculate: (bitmap[0] & 0x08) != 0.
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+ // To retrieve bit n, calculate: (bitmap[n / 8] & (0x01 << (n % 8))) != 0.
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+ //
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+ // The "size" of a `BitSequence` (the number of bits it contains) is calculated
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+ // by this formula: (bitmap.length * 8) - padding.
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+ message BitSequence {
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+ // The bytes that encode the bit sequence.
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+ // May have a length of zero.
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+ bytes bitmap = 1 ;
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+
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+ // The number of bits of the last byte in `bitmap` to ignore as "padding".
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+ // If the length of `bitmap` is zero, then this value must be 0.
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+ // Otherwise, this value must be between 0 and 7, inclusive.
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+ int32 padding = 2 ;
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+ }
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+
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+ // A bloom filter (https://en.wikipedia.org/wiki/Bloom_filter).
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+ //
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+ // The bloom filter hashes the entries with MD5 and treats the resulting 128-bit
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+ // hash as 2 distinct 64-bit hash values, interpreted as unsigned integers
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+ // using 2's complement encoding.
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+ //
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+ // These two hash values, named h1 and h2, are then used to compute the
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+ // `hash_count` hash values using the formula, starting at i=0:
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+ //
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+ // h(i) = h1 + (i * h2)
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+ //
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+ // These resulting values are then taken modulo the number of bits in the bloom
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+ // filter to get the bits of the bloom filter to test for the given entry.
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+ message BloomFilter {
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+ // The bloom filter data.
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+ BitSequence bits = 1 ;
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+
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+ // The number of hashes used by the algorithm.
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+ int32 hash_count = 2 ;
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+ }
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