CmdStan now installs when the first model is compiled rather than on …

…gem installation

.github/workflows/build.yml

@@ -5,13 +5,18 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest] # TODO add windows-latest
+        include:
+        - ruby: 3.1
+          os: ubuntu-20.04
+        - ruby: "3.0"
+          os: ubuntu-18.04
+        - ruby: 2.7
+          os: macos-latest
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2
     - uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 3.1
+        ruby-version: ${{ matrix.ruby }}
         bundler-cache: true
-    - run: bundle exec ruby ext/cmdstan/extconf.rb
     - run: bundle exec rake test

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## 0.2.0 (unreleased)
 
+- CmdStan now installs when the first model is compiled rather than on gem installation
+- Added `install_cmdstan` method
+- Updated CmdStan to 2.29.2
 - Fixed issue with `summary` method
 - Dropped support for Ruby < 2.7
 

README.md

@@ -12,8 +12,6 @@ Add this line to your application’s Gemfile:
 gem "cmdstan"
 ```
 
-Installation can take a few minutes as CmdStan downloads and builds.
-
 ## Getting Started
 
 Create a Stan file, like `bernoulli.stan`
@@ -32,7 +30,7 @@ model {
 }
 ```
 
-Compile the model
+Compile the model (this can take a few minutes the first time as CmdStan downloads and builds)
 
 ```ruby
 model = CmdStan::Model.new(stan_file: "bernoulli.stan")
@@ -51,13 +49,33 @@ Summarize the results
 fit.summary
 ```
 
+Load a compiled model
+
+```ruby
+model = CmdStan::Model.new(exe_file: "bernoulli")
+```
+
 ## Maximum Likelihood Estimation
 
 ```ruby
 mle = model.optimize(data: data)
 mle.optimized_params
 ```
 
+## Reference
+
+Check if CmdStan is installed
+
+```ruby
+CmdStan.cmdstan_installed?
+```
+
+Install CmdStan manually
+
+```ruby
+CmdStan.install_cmdstan
+```
+
 ## Credits
 
 This library is modeled after the [CmdStanPy API](https://github.com/stan-dev/cmdstanpy).
@@ -81,6 +99,5 @@ To get started with development:
 git clone https://github.com/ankane/cmdstan-ruby.git
 cd cmdstan-ruby
 bundle install
-bundle exec ruby ext/cmdstan/extconf.rb
 bundle exec rake test
 ```

cmdstan.gemspec

@@ -10,9 +10,8 @@ Gem::Specification.new do |spec|
   spec.author        = "Andrew Kane"
   spec.email         = "andrew@ankane.org"
 
-  spec.files         = Dir["*.{md,txt}", "{ext,lib}/**/*"]
+  spec.files         = Dir["*.{md,txt}", "{lib}/**/*"]
   spec.require_path  = "lib"
-  spec.extensions    = ["ext/cmdstan/extconf.rb"]
 
   spec.required_ruby_version = ">= 2.7"
 end

lib/cmdstan.rb

@@ -1,10 +1,14 @@
 # stdlib
+require "digest"
 require "csv"
+require "fileutils"
 require "json"
+require "net/http"
 require "open3"
 require "tempfile"
 
 # modules
+require "cmdstan/install"
 require "cmdstan/utils"
 require "cmdstan/mcmc"
 require "cmdstan/mle"
@@ -14,6 +18,8 @@
 module CmdStan
   class Error < StandardError; end
 
+  extend Install
+
   class << self
     attr_accessor :path
   end

lib/cmdstan/install.rb

@@ -0,0 +1,100 @@
+module CmdStan
+  module Install
+    def cmdstan_version
+      "2.29.2"
+    end
+
+    def cmdstan_installed?
+      Dir.exist?(CmdStan.path)
+    end
+
+    def install_cmdstan
+      version = cmdstan_version
+      dir = CmdStan.path
+
+      # TODO figure out Mac ARM
+      if RbConfig::CONFIG["host_os"] !~ /darwin/i && RbConfig::CONFIG["host_cpu"] =~ /arm|aarch64/i
+        checksum = "9b7eec78e217cab39d3d794e817a1ca08f36b1e5cb434c4cd8263bb2650ba125"
+        url = "https://github.com/stan-dev/cmdstan/releases/download/v#{version}/cmdstan-#{version}-linux-arm64.tar.gz"
+      else
+        checksum = "567b531fa73ffdf706caa17eb3344e1dfb41e86993caf8ba40875ff910335153"
+        url = "https://github.com/stan-dev/cmdstan/releases/download/v#{version}/cmdstan-#{version}.tar.gz"
+      end
+
+      puts "Installing CmdStan version: #{version}"
+      puts "Install directory: #{dir}"
+
+      # only needed if default path
+      FileUtils.mkdir_p(File.expand_path("../../tmp", __dir__)) unless ENV["CMDSTAN"]
+
+      if Dir.exist?(dir)
+        puts "Already installed"
+        return true
+      end
+
+      Dir.mktmpdir do |tmpdir|
+        puts "Downloading..."
+        download_path = File.join(tmpdir, "cmdstan-#{version}.tar.gz")
+        download_file(url, download_path, checksum)
+
+        puts "Unpacking..."
+        path = File.join(tmpdir, "cmdstan-#{version}")
+        FileUtils.mkdir_p(path)
+        tar_args = Gem.win_platform? ? ["--force-local"] : []
+        system "tar", "xzf", download_path, "-C", path, "--strip-components=1", *tar_args
+
+        puts "Building..."
+        make_command = Gem.win_platform? ? "mingw32-make" : "make"
+        Dir.chdir(path) do
+          # disable precompiled header to save space
+          output, status = Open3.capture2e(make_command, "build", "PRECOMPILED_HEADERS=false")
+          if status.exitstatus != 0
+            puts output
+            raise Error, "Build failed"
+          end
+        end
+
+        FileUtils.mv(path, dir)
+      end
+
+      puts "Installed"
+
+      true
+    end
+
+    private
+
+    def download_file(url, download_path, checksum, redirects = 0)
+      raise Error, "Too many redirects" if redirects > 10
+
+      uri = URI(url)
+      location = nil
+
+      Net::HTTP.start(uri.host, uri.port, use_ssl: true) do |http|
+        request = Net::HTTP::Get.new(uri)
+        http.request(request) do |response|
+          case response
+          when Net::HTTPRedirection
+            location = response["location"]
+          when Net::HTTPSuccess
+            digest = Digest::SHA2.new
+
+            File.open(download_path, "wb") do |f|
+              response.read_body do |chunk|
+                f.write(chunk)
+                digest.update(chunk)
+              end
+            end
+
+            raise Error, "Bad checksum: #{digest.hexdigest}" if digest.hexdigest != checksum
+          else
+            raise Error, "Bad response"
+          end
+        end
+      end
+
+      # outside of Net::HTTP block to close previous connection
+      download_file(location, download_path, checksum, redirects + 1) if location
+    end
+  end
+end

lib/cmdstan/model.rb

@@ -18,8 +18,12 @@ def initialize(stan_file: nil, exe_file: nil, compile: true)
     end
 
     def compile
+      unless ENV["CMDSTAN"] || CmdStan.cmdstan_installed?
+        CmdStan.install_cmdstan
+      end
+
       Dir.chdir(CmdStan.path) do
-        run_command make_command, @exe_file
+        run_command make_command, @exe_file, "PRECOMPILED_HEADERS=false"
       end
     end
 

test/model_test.rb

@@ -53,6 +53,11 @@ def test_works
     assert_equal ["lp__", "theta"], mle.column_names
     assert_in_delta(-5.00402, mle.optimized_params["lp__"])
     assert_in_delta(0.2, mle.optimized_params["theta"])
+
+    # load model
+    model = CmdStan::Model.new(exe_file: model.exe_file)
+    fit = model.sample(chains: 5, data: data, seed: 123)
+    assert_equal 1000, fit.draws
   end
 
   private