Minimal parachain framework part 1 (#113)

* dynamic inclusion threshold calculator

* collators interface

* collation helpers

* initial proposal-creation future

* create proposer when asked to propose

* remove local_availability duty

* statement table tracks includable parachain count

* beginnings of timing future

* finish proposal logic

* remove stray println

* extract shared table to separate module

* change ordering

* includability tracking

* fix doc

* initial changes to parachains module

* initialise dummy block before API calls

* give polkadot control over round proposer based on random seed

* propose only after enough candidates

* flesh out parachains module a bit more

* set_heads

* actually introduce set_heads to runtime

* update block_builder to accept parachains

* split block validity errors from real errors in evaluation

* update WASM runtimes

* polkadot-api methods for parachains additions

* delay evaluation until candidates are ready

* comments

* fix dynamic inclusion with zero initial

* test for includability tracker

* wasm validation of parachain candidates

* move primitives to primitives crate

* remove runtime-std dependency from codec

* adjust doc

* polkadot-parachain-primitives

* kill legacy polkadot-validator crate

* basic-add test chain

* test for basic_add parachain

* move to test-chains dir

* use wasm-build

* new wasm directory layout

* reorganize a bit more

* Fix for rh-minimal-parachain (#141)

* Remove extern "C"

We already encountered such behavior (bug?) in pwasm-std, I believe.

* Fix `panic_fmt` signature by adding `_col`

Wrong `panic_fmt` signature can inhibit some optimizations in LTO mode.

* Add linker flags and use wasm-gc in build script

Pass --import-memory to LLD to emit wasm binary with imported memory.

Also use wasm-gc instead of wasm-build.

* Fix effective_max.

I'm not sure why it was the way it was actually.

* Recompile wasm.

* Fix indent

* more basic_add tests

* validate parachain WASM

* produce statements on receiving statements

* tests for reactive statement production

* fix build

* add OOM lang item to runtime-io

* use dynamic_inclusion when evaluating as well

* fix update_includable_count

* remove dead code

* grumbles

* actually defer round_proposer logic

* update wasm

* address a few more grumbles

* grumbles

* update WASM checkins

* remove dependency on tokio-timer

polkadot/transaction-pool/src/lib.rs

@@ -36,7 +36,8 @@ use std::sync::Arc;
 
 use polkadot_api::PolkadotApi;
 use primitives::{AccountId, Timestamp};
-use runtime::{Block, UncheckedExtrinsic, TimestampCall, Call};
+use primitives::parachain::CandidateReceipt;
+use runtime::{Block, UncheckedExtrinsic, TimestampCall, ParachainsCall, Call};
 use substrate_runtime_primitives::traits::{Bounded, Checkable};
 use transaction_pool::{Pool, Readiness};
 use transaction_pool::scoring::{Change, Choice};
@@ -59,17 +60,26 @@ pub struct PolkadotBlock {
 impl PolkadotBlock {
 	/// Create a new block, checking high-level well-formedness.
 	pub fn from(unchecked: Block) -> ::std::result::Result<Self, Block> {
-		if unchecked.extrinsics.len() < 1 {
+		if unchecked.extrinsics.len() < 2 {
 			return Err(unchecked);
 		}
 		if unchecked.extrinsics[0].is_signed() {
 			return Err(unchecked);
 		}
+		if unchecked.extrinsics[1].is_signed() {
+			return Err(unchecked);
+		}
+
 		match unchecked.extrinsics[0].extrinsic.function {
 			Call::Timestamp(TimestampCall::set(_)) => {},
 			_ => return Err(unchecked),
 		}
 
+		match unchecked.extrinsics[1].extrinsic.function {
+			Call::Parachains(ParachainsCall::set_heads(_)) => {},
+			_ => return Err(unchecked),
+		}
+
 		// any further checks...
 		Ok(PolkadotBlock { block: unchecked, location: None })
 	}
@@ -92,6 +102,19 @@ impl PolkadotBlock {
 			}
 		}
 	}
+
+	/// Retrieve the parachain candidates proposed for this block.
+	pub fn parachain_heads(&self) -> &[CandidateReceipt] {
+		if let Call::Parachains(ParachainsCall::set_heads(ref t)) = self.block.extrinsics[1].extrinsic.function {
+			&t[..]
+		} else {
+			if let Some((file, line)) = self.location {
+				panic!("Invalid block used in `PolkadotBlock::force_from` at {}:{}", file, line);
+			} else {
+				panic!("Invalid block made it through the PolkadotBlock verification!?");
+			}
+		}
+	}
 }
 
 #[macro_export]