default max_pool_size to 0 = unlimited

src/db/database.cr

@@ -7,7 +7,7 @@ module DB
   # The connection pool can be configured from URI parameters:
   #
   #   - initial_pool_size (default 1)
-  #   - max_pool_size (default 1)
+  #   - max_pool_size (default 0 = unlimited)
   #   - max_idle_pool_size (default 1)
   #   - checkout_timeout (default 5.0)
   #   - retry_attempts (default 1)

src/db/driver.cr

@@ -31,7 +31,7 @@ module DB
     def connection_pool_options(params : HTTP::Params)
       {
         initial_pool_size:  params.fetch("initial_pool_size", 1).to_i,
-        max_pool_size:      params.fetch("max_pool_size", 1).to_i,
+        max_pool_size:      params.fetch("max_pool_size", 0).to_i,
         max_idle_pool_size: params.fetch("max_idle_pool_size", 1).to_i,
         checkout_timeout:   params.fetch("checkout_timeout", 5.0).to_f,
         retry_attempts:     params.fetch("retry_attempts", 1).to_i,

src/db/pool.cr

@@ -12,7 +12,7 @@ module DB
     @retry_attempts : Int32
     @retry_delay : Float64
 
-    def initialize(@initial_pool_size = 1, @max_pool_size = 1, @max_idle_pool_size = 1, @checkout_timeout = 5.0,
+    def initialize(@initial_pool_size = 1, @max_pool_size = 0, @max_idle_pool_size = 1, @checkout_timeout = 5.0,
                    @retry_attempts = 1, @retry_delay = 0.2, &@factory : -> T)
       @initial_pool_size.times { build_resource }
 
@@ -124,7 +124,7 @@ module DB
     end
 
     private def can_increase_pool
-      @total.size < @max_pool_size
+      @max_pool_size == 0 || @total.size < @max_pool_size
     end
 
     private def can_increase_idle_pool