From 304c581005a34f9df9a5e6ea7158969db5f5a079 Mon Sep 17 00:00:00 2001
From: BlackMATov <blackmat@mail.ru>
Date: Fri, 22 Nov 2024 08:56:27 +0700
Subject: [PATCH] simple idpools module

---
 .vscode/extensions.json             |  3 +-
 develop/untests.lua                 |  2 +-
 develop/untests/idpools_untests.lua | 85 +++++++++++++++++++++++++++++
 evolved/evolved.lua                 |  1 +
 evolved/idpools.lua                 | 69 +++++++++++++++++++++++
 5 files changed, 158 insertions(+), 2 deletions(-)
 create mode 100644 develop/untests/idpools_untests.lua
 create mode 100644 evolved/idpools.lua

diff --git a/.vscode/extensions.json b/.vscode/extensions.json
index d9b86f8..533d0a2 100644
--- a/.vscode/extensions.json
+++ b/.vscode/extensions.json
@@ -1,5 +1,6 @@
 {
     "recommendations": [
-        "sumneko.lua"
+        "sumneko.lua",
+        "tomblind.local-lua-debugger-vscode"
     ]
 }
diff --git a/develop/untests.lua b/develop/untests.lua
index 67ce65b..391df24 100644
--- a/develop/untests.lua
+++ b/develop/untests.lua
@@ -1 +1 @@
-local evo = require 'evolved.evolved'
+require 'develop.untests.idpools_untests'
diff --git a/develop/untests/idpools_untests.lua b/develop/untests/idpools_untests.lua
new file mode 100644
index 0000000..ff0e23b
--- /dev/null
+++ b/develop/untests/idpools_untests.lua
@@ -0,0 +1,85 @@
+local evo = require 'evolved.evolved'
+
+do
+    local p1 = evo.idpools.idpool()
+    local p2 = evo.idpools.idpool()
+    assert(p1 ~= p2)
+end
+
+do
+    local p = evo.idpools.idpool()
+
+    local i1_1 = evo.idpools.acquire_id(p)
+    assert(i1_1 == 0x100001)
+
+    local i2_1 = evo.idpools.acquire_id(p)
+    assert(i2_1 == 0x100002)
+
+    do
+        local i, v = evo.idpools.unpack_id(i1_1)
+        assert(i == 1 and v == 1)
+    end
+
+    do
+        local i, v = evo.idpools.unpack_id(i2_1)
+        assert(i == 2 and v == 1)
+    end
+end
+
+do
+    local p = evo.idpools.idpool()
+
+    local i1_1 = evo.idpools.acquire_id(p)
+    local i2_1 = evo.idpools.acquire_id(p)
+    assert(evo.idpools.is_id_alive(p, i1_1))
+    assert(evo.idpools.is_id_alive(p, i2_1))
+
+    evo.idpools.release_id(p, i1_1)
+    assert(not evo.idpools.is_id_alive(p, i1_1))
+    assert(evo.idpools.is_id_alive(p, i2_1))
+
+    evo.idpools.release_id(p, i2_1)
+    assert(not evo.idpools.is_id_alive(p, i1_1))
+    assert(not evo.idpools.is_id_alive(p, i2_1))
+
+    local i2_2 = evo.idpools.acquire_id(p)
+    assert(i2_2 == 0x200002)
+
+    local i1_2 = evo.idpools.acquire_id(p)
+    assert(i1_2 == 0x200001)
+
+    assert(not evo.idpools.is_id_alive(p, i1_1))
+    assert(not evo.idpools.is_id_alive(p, i2_1))
+    assert(evo.idpools.is_id_alive(p, i1_2))
+    assert(evo.idpools.is_id_alive(p, i2_2))
+end
+
+do
+    local p = evo.idpools.idpool()
+
+    for _ = 1, 0xFFFFF - 1 do
+        _ = evo.idpools.acquire_id(p)
+    end
+
+    assert(evo.idpools.acquire_id(p) == 0x1FFFFF)
+
+    if not os.getenv("LOCAL_LUA_DEBUGGER_VSCODE") then
+        assert(not pcall(evo.idpools.acquire_id, p))
+    end
+end
+
+do
+    local p = evo.idpools.idpool()
+
+    for _ = 1, 0x7FF - 1 do
+        evo.idpools.release_id(p, evo.idpools.acquire_id(p))
+    end
+
+    local i1_7FF = evo.idpools.acquire_id(p)
+    assert(i1_7FF == 0x7FF00001)
+    evo.idpools.release_id(p, i1_7FF)
+
+    local i1_1 = evo.idpools.acquire_id(p)
+    assert(i1_1 == 0x100001)
+    evo.idpools.release_id(p, i1_1)
+end
diff --git a/evolved/evolved.lua b/evolved/evolved.lua
index 10a78cd..5996e8a 100644
--- a/evolved/evolved.lua
+++ b/evolved/evolved.lua
@@ -1,4 +1,5 @@
 return {
+    idpools = require 'evolved.idpools',
     registry = require 'evolved.registry',
     singles = require 'evolved.singles',
     vectors = require 'evolved.vectors',
diff --git a/evolved/idpools.lua b/evolved/idpools.lua
new file mode 100644
index 0000000..e69b388
--- /dev/null
+++ b/evolved/idpools.lua
@@ -0,0 +1,69 @@
+local bit = require 'bit'
+
+---@class evolved.idpools
+local idpools = {}
+
+---@class evolved.idpool
+---@field acquired_ids integer[]
+---@field available_index integer
+local evolved_idpool_mt = {}
+evolved_idpool_mt.__index = evolved_idpool_mt
+
+---@return evolved.idpool
+function idpools.idpool()
+    ---@type evolved.idpool
+    local self = {
+        acquired_ids = {},
+        available_index = 0,
+    }
+    return setmetatable(self, evolved_idpool_mt)
+end
+
+---@param id integer
+---@return integer index
+---@return integer version
+function idpools.unpack_id(id)
+    return bit.band(id, 0xFFFFF), bit.rshift(id, 20)
+end
+
+---@param idpool evolved.idpool
+---@return integer
+---@nodiscard
+function idpools.acquire_id(idpool)
+    if idpool.available_index ~= 0 then
+        local index = idpool.available_index
+        local version = bit.band(idpool.acquired_ids[index], 0x7FF00000)
+        idpool.available_index = bit.band(idpool.acquired_ids[index], 0xFFFFF)
+        idpool.acquired_ids[index] = index + version
+        return idpool.acquired_ids[index]
+    end
+
+    if #idpool.acquired_ids == 0xFFFFF then
+        error('id index overflow', 2)
+    end
+
+    local index, version = #idpool.acquired_ids + 1, 0x100000
+    idpool.acquired_ids[index] = index + version
+    return idpool.acquired_ids[index]
+end
+
+---@param idpool evolved.idpool
+---@param id integer
+function idpools.release_id(idpool, id)
+    local index = bit.band(id, 0xFFFFF)
+    local version = bit.band(id, 0x7FF00000)
+    version = version == 0x7FF00000 and 0x100000 or version + 0x100000
+    idpool.acquired_ids[index] = idpool.available_index + version
+    idpool.available_index = index
+end
+
+---@param idpool evolved.idpool
+---@param id integer
+---@return boolean
+---@nodiscard
+function idpools.is_id_alive(idpool, id)
+    local index = bit.band(id, 0xFFFFF)
+    return idpool.acquired_ids[index] == id
+end
+
+return idpools