feature: Round Robin with optional random start #26
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ElvinEfendi
changed the title
README.markdown
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| @@ -126,7 +126,7 @@ Both `resty.chash` and `resty.roundrobin` have the same apis. | |||
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| new | |||
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| **syntax:** `obj, err = class.new(nodes)` | |||
| **syntax:** `obj, err = class.new(nodes, random_start?)` | |||
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I think we can always make it start randomly.
lib/resty/roundrobin.lua
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| @@ -46,18 +47,40 @@ local function get_gcd(nodes) | |||
| return only_key, gcd, max_weight | |||
| end | |||
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| local function get_random_node_id(nodes) | |||
| local count = 0 | |||
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style: need four space as indent.
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@doujiang24 thanks for quick review! I addressed your comments. |
lib/resty/roundrobin.lua
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| local function get_random_node_id(nodes) | ||
| local count = 0 | ||
| for _, _ in pairs(nodes) do | ||
| count = count + 1 |
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style: need four space too :)
lib/resty/roundrobin.lua
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| local random_index = math_random(count) | ||
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| for _ = 1, random_index do | ||
| id = next(nodes, id) |
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oops, I missed them - fixed now
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Is there anything else I can do to get this merged and released? |
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@doujiang24 any plan here? |
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@doujiang24 when are you planning on releasing this? |
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@ElvinEfendi |
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@doujiang24 thanks! Does it get automatically published to Luarocks? Or do you suggest using OPM? |
not yet.
OPM doesn't support this library yet since it only supports pure Lua library now. |
It's sometimes useful to have Round Robin algorithm to start with a random node in the given list instead of always starting with the first one. Imagine you have 50 replicas on Nginx and in each replica 16 workers. That means all 50*16 requests will end up in the first server.
For another real world use case please refer to the thread in kubernetes/ingress-nginx#4023 (comment).
This PR adds an optional flag to Round Robin initializer and if the flag is set it picks
last_idat random instead of setting it to `nil.