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99 lines
1.8 KiB
99 lines
1.8 KiB
require "sqlite3"
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require "../config.cr"
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class CacheLRU
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def initialize
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@store = Hash(String, Tuple(Time, User)).new
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@mutex = Mutex.new
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@cache_limit = 5000
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end
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def try(pair) : User | Nil
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@mutex.synchronize do
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if @store.has_key?(pair)
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return @store[pair][1]
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else return nil
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end
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end
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end
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def push(pair, data)
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@mutex.synchronize do
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@store[pair] = Tuple.new(Time.now+Time::Span.new(1,0,0), data)
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if(@store.size > @cache_limit)
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clean
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end
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end
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end
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def clean
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@mutex.synchronize do
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curr = Time.now
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@store.reject! do |k, v|
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return v[0]>curr
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end
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end
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end
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def invalidate(pair)
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@mutex.synchronize do
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@store.reject! pair
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end
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end
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end
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class KVStore
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property database : DB::Database
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property st_fetch : DB::PoolPreparedStatement
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property st_push : DB::PoolPreparedStatement
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property cache : CacheLRU
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def initialize
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@database = DB.open(Statics.data_path)
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@database.exec "create table if not exists kv (k TEXT PRIMARY KEY, v TEXT);"
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@st_fetch = DB::PoolPreparedStatement.new @database, "select v from kv where k=?;"
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@st_push = DB::PoolPreparedStatement.new @database, "insert into kv(k,v) values(?,?) on conflict(k) do update set v=?;"
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@cache = CacheLRU.new
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end
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def fetch(key : String) : User | Nil
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begin
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f = @cache.try(key)
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if(f.nil?)
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v = @st_fetch.scalar(key)
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u = User.from_json v.to_s
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@cache.push(key, u)
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if(v.nil?)
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return nil
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else
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return u
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end
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else
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return f
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end
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rescue ex
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return nil
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end
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end
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def fetch!(key : String) : User
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fetch(key).not_nil!
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end
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def push(key : String, value : String)
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@cache.invalidate key
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@st_push.exec(key, value, value)
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end
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def transaction()
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@database.transaction do |tx|
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yield self
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end
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end
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def self.access
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@@instance ||= new
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end
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end
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