Module: Protocol::GRPC::Metadata

Defined in:
lib/protocol/grpc/metadata.rb

Overview

Provides operations for building and extracting gRPC metadata.

Class Method Summary collapse

Class Method Details

.assign_status!(headers, status: Status::OK, message: nil, error: nil) ⇒ Object Also known as: add_status!

Assign gRPC status, message, and optional backtrace to headers.

Whether these become headers or trailers is controlled by the protocol layer.



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# File 'lib/protocol/grpc/metadata.rb', line 111

def self.assign_status!(headers, status: Status::OK, message: nil, error: nil)
	headers["grpc-status"] = status
	
	if error && message.nil?
		# If message is not provided but error is, use error message
		message = error.message
	end
	
	if message
		headers["grpc-message"] = message
	end
	
	# Add backtrace from error if available
	if error && error.backtrace && !error.backtrace.empty?
		# Assign backtrace array directly - Split header will handle it
		headers["backtrace"] = error.backtrace
	end
	
	return headers
end

.build(metadata: {}, timeout: nil, content_type: "application/grpc+proto") ⇒ Object

Build gRPC request headers containing the given metadata.



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# File 'lib/protocol/grpc/metadata.rb', line 20

def self.build(metadata: {}, timeout: nil, content_type: "application/grpc+proto")
	headers = Protocol::HTTP::Headers.new(policy: Protocol::GRPC::HEADER_POLICY)
	headers["content-type"] = content_type
	headers["te"] = "trailers"
	
	if timeout
		# Coerced to proper format by header policy:
		headers["grpc-timeout"] = timeout
	end
	
	metadata.each do |key, value|
		# Binary headers end with -bin and are base64 encoded:
		headers[key] = if key.end_with?("-bin")
			Base64.strict_encode64(value)
		else
			value.to_s
		end
	end
	
	headers
end

.extract(headers) ⇒ Object

Extract application metadata from gRPC headers.



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# File 'lib/protocol/grpc/metadata.rb', line 45

def self.extract(headers)
	metadata = {}
	
	headers.to_h.each do |key, value|
		# Skip reserved headers:
		next if key.start_with?("grpc-") || key == "content-type" || key == "te"
		
		# Decode binary headers:
		if key.end_with?("-bin")
			if value.is_a?(String)
				value = Base64.strict_decode64(value)
			elsif value.is_a?(Array)
				value = value.map{|item| Base64.strict_decode64(item)}
			end
		end
		
		metadata[key] = value
	end
	
	metadata
end

.extract_message(headers) ⇒ Object

Extract gRPC status message from headers. Returns Nil if message is not present.



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# File 'lib/protocol/grpc/metadata.rb', line 92

def self.extract_message(headers)
	# Ensure policy is set - setting policy clears the index (@indexed = nil)
	# The index will be rebuilt automatically on next access via to_h
	headers.policy = Protocol::GRPC::HEADER_POLICY unless headers.policy == Protocol::GRPC::HEADER_POLICY
	
	message = headers["grpc-message"]
	return nil unless message
	
	return message.decode
end

.extract_status(headers) ⇒ Object

Extract gRPC status from headers. Returns Status::UNKNOWN if status is not present.

Note: In Protocol::HTTP::Headers, trailers are merged into the headers so users just access headers regardless of whether it was sent as an initial header or trailer.



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# File 'lib/protocol/grpc/metadata.rb', line 76

def self.extract_status(headers)
	# Ensure policy is set - setting policy clears the index (@indexed = nil)
	# The index will be rebuilt automatically on next access via to_h
	headers.policy = Protocol::GRPC::HEADER_POLICY unless headers.policy == Protocol::GRPC::HEADER_POLICY
	
	status = headers["grpc-status"]
	return Status::UNKNOWN unless status
	
	return status.to_i
end