forked from TrueCloudLab/frostfs-node
Evgenii Stratonikov
001a23eb31
JSON format is rather verbose an inconvenient to be edited by hand. This commit implements SQL-like language for representing placement policy. Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
20 lines
861 B
Go
20 lines
861 B
Go
// Package policy provides facilities for creating policy from SQL-like language.
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// eBNF grammar is provided in `grammar.ebnf` for illustration.
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//
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// Current limitations:
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// 1. Grouping filter expressions in parenthesis is not supported right now.
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// Requiring this will make query too verbose, making it optional makes
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// our grammar not LL(1). This can be supported in future.
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// 2. Filters must be defined before they are used.
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// This requirement may be relaxed in future.
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//
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// Example query:
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// REP 1 in SPB
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// REP 2 in Americas
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// CBF 4
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// SELECT 1 Node IN City FROM SPBSSD AS SPB
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// SELECT 2 Node IN SAME City FROM Americas AS Americas
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// FILTER SSD EQ true AS IsSSD
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// FILTER @IsSSD AND Country eq "RU" AND City eq "St.Petersburg" AS SPBSSD
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// FILTER 'Continent' == 'North America' OR Continent == 'South America' AS Americas
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package policy
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