fix(async): slightly better support for nested coroutine contexts (#600)

* fix(async): only dispatch first failure in a.wait_all

* add InstallContext:run_concurrently

This is needed due to how multiple coroutine contexts are used in a hierchical
structure, and the async coroutine dispatcher loses this hierchical context
inside callback functions invoked via FFI (I… assume?).

4 files changed, 37 insertions, 14 deletions

diff --git a/lua/nvim-lsp-installer/core/async/init.lua b/lua/nvim-lsp-installer/core/async/init.lua
index 8537b909..27a4c7cb 100644
--- a/lua/nvim-lsp-installer/core/async/init.lua
+++ b/lua/nvim-lsp-installer/core/async/init.lua
@@ -147,6 +147,9 @@ local function oneshot_channel()
     local saved_callback
 
     return {
+        is_closed = function()
+            return has_sent
+        end,
         send = function(...)
             assert(not has_sent, "Oneshot channel can only send once.")
             has_sent = true
@@ -174,32 +177,31 @@ exports.wait_all = function(suspend_fns)
 
     do
         local results = {}
-        local threads = {}
+        local thread_cancellations = {}
         local count = #suspend_fns
         local completed = 0
 
-        local function callback(i)
-            return function(success, result)
+        for i, suspend_fn in ipairs(suspend_fns) do
+            thread_cancellations[i] = exports.run(suspend_fn, function(success, result)
+                completed = completed + 1
                 if not success then
-                    for _, cancel_thread in ipairs(threads) do
-                        cancel_thread()
+                    if not channel.is_closed() then
+                        for _, cancel_thread in ipairs(thread_cancellations) do
+                            cancel_thread()
+                        end
+                        channel.send(false, result)
+                        results = nil
+                        thread_cancellations = {}
                     end
-                    channel.send(false, result)
-                    results = nil
-                    threads = nil
                 else
                     results[i] = result
-                    completed = completed + 1
                     if completed >= count then
                         channel.send(true, results)
                         results = nil
-                        threads = nil
+                        thread_cancellations = {}
                     end
                 end
-            end
-        end
-        for i, suspend_fn in ipairs(suspend_fns) do
-            threads[i] = exports.run(suspend_fn, callback(i))
+            end)
         end
     end
 
diff --git a/lua/nvim-lsp-installer/core/installer/context.lua b/lua/nvim-lsp-installer/core/installer/context.lua
index 5705fa41..f97f334f 100644
--- a/lua/nvim-lsp-installer/core/installer/context.lua
+++ b/lua/nvim-lsp-installer/core/installer/context.lua
@@ -4,6 +4,8 @@ local fs = require "nvim-lsp-installer.core.fs"
 local path = require "nvim-lsp-installer.path"
 local platform = require "nvim-lsp-installer.platform"
 local receipt = require "nvim-lsp-installer.core.receipt"
+local installer = require "nvim-lsp-installer.core.installer"
+local a = require "nvim-lsp-installer.core.async"
 
 ---@class ContextualSpawn
 ---@field cwd CwdManager
@@ -139,4 +141,17 @@ function InstallContext:promote_cwd()
     self.cwd:set(self.destination_dir)
 end
 
+---Runs the provided async functions concurrently and returns their result, once all are resolved.
+---This is really just a wrapper around a.wait_all() that makes sure to patch the coroutine context before creating the
+---new async execution contexts.
+---@async
+---@param suspend_fns async fun(ctx: InstallContext)[]
+function InstallContext:run_concurrently(suspend_fns)
+    return a.wait_all(vim.tbl_map(function(suspend_fn)
+        return function()
+            return installer.run_installer(self, suspend_fn)
+        end
+    end, suspend_fns))
+end
+
 return InstallContext
diff --git a/lua/nvim-lsp-installer/core/installer/init.lua b/lua/nvim-lsp-installer/core/installer/init.lua
index dc9143a2..888415f2 100644
--- a/lua/nvim-lsp-installer/core/installer/init.lua
+++ b/lua/nvim-lsp-installer/core/installer/init.lua
@@ -34,6 +34,7 @@ end
 function M.run_installer(context, installer)
     local thread = coroutine.create(installer)
     local step
+    local ret_val
     step = function(...)
         local ok, result = coroutine.resume(thread, ...)
         if not ok then
@@ -43,9 +44,12 @@ function M.run_installer(context, installer)
         elseif coroutine.status(thread) == "suspended" then
             -- yield to parent coroutine
             step(coroutine.yield(result))
+        else
+            ret_val = result
         end
     end
     step(context)
+    return ret_val
 end
 
 ---@async
diff --git a/lua/nvim-lsp-installer/core/managers/powershell/init.lua b/lua/nvim-lsp-installer/core/managers/powershell/init.lua
index a246e24c..94046b05 100644
--- a/lua/nvim-lsp-installer/core/managers/powershell/init.lua
+++ b/lua/nvim-lsp-installer/core/managers/powershell/init.lua
@@ -11,6 +11,7 @@ local PWSHOPT = {
 ---@param script string
 ---@param opts JobSpawnOpts
 ---@param custom_spawn JobSpawn
+---@return Result
 function M.script(script, opts, custom_spawn)
     opts = opts or {}
     ---@type JobSpawn
@@ -31,6 +32,7 @@ end
 ---@param command string
 ---@param opts JobSpawnOpts
 ---@param custom_spawn JobSpawn
+---@return Result
 function M.command(command, opts, custom_spawn)
     opts = opts or {}
     ---@type JobSpawn