• Nils Goroll's avatar
    shard director: LAZY mode (vdi resolve function), parameter objects · 9b8f6e21
    Nils Goroll authored
    We introduce a shard_param object to hold the shard director lookup
    parameters which until now could only be passed to the .backend()
    method.
    
    By associating a parameter object with a shard director, we enable
    LAZY lookups as with the other directors. Parameter objects are
    defined with VCL scope (normal vmod objects), but can be overridden
    per backend request using a task priv.
    
    We use the same concept to carry shard.backend() parameters to
    vdi resolve for LAZY mode: They get saved in a per-director task
    scope parameter object.
    
    Each object points to another object providing defaults for
    values which are not defined.
    
    Actual resolution of the various parameter objects does not happen
    before they are used to allow changing them independently (ie,
    shard .backend() parameters have precedence over an associated
    parameter object, which by itself can be overridden).
    
    Overview of parameter objects (pointers are alternatives)
    
    shard() director	shard_param() object	default praram
    
    	     --------------------------------->	  vmod static
      VCL obj   /				     ->
      .param  -+--------->	  VCL obj	    /  _
      			  .default  --------   /|
    					      /
    			     ^		     /
    			     |		    /
    					   /
    			  .default	  /
    	------------->	  TASK priv	 /
           /				/
      .default -----------------------------
      TASK priv
    9b8f6e21
d00029.vtc 1.52 KB