Subscribe to Runtime upgrades for proper extrinsic construction (#513)

* subxt: Add subscription to runtime upgrades

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Synchronize and expose inner `RuntimeVersion` of the `Client`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Add runtime update example

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Expose `RuntimeVersion` as locked

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Expose `Metadata` as locked

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt/storage: Use locked metadata

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Use parking lot RwLock variant for locked metadata

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Utilize locked metadata variant

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt/transaction: Use locked metadata variant

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update subxt to use locked version of the Metadata

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Add runtime update client wrapper

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Modify runtime update example

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Fix clippy

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Fix cargo check

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Keep consistency with cargo check fix

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Remove unnecessary Arc

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Remove MetadataInner and use parking_lot::RwLock

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update polkadot.rs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update polkadot.rs generation comment

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Switch to async::Mutex

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Block executor while decoding dynamic events

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Use async API to handle async locking

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Remove unused dependencies

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update examples and integration-tests

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Fix test deadlock

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Revert back to sync lock

Revert "Fix test deadlock"

This reverts commit 4a79933df23e81573611cb14be6c5b5b2b56d4df.

Revert "Update examples and integration-tests"

This reverts commit 5423f6eb4131582909d5a4ca70adff75e27cdd0e.

Revert "Remove unused dependencies"

This reverts commit e8ecbabb5b01a7ba4ae83b8bde36295a3f64daf7.

Revert "codegen: Use async API to handle async locking"

This reverts commit ced4646541c431adcb973369b1061b7b3cbfaae1.

Revert "subxt: Block executor while decoding dynamic events"

This reverts commit 8b3ba4a5eabb29f77ac1ca671450956fc479a33d.

Revert "subxt: Switch to async::Mutex"

This reverts commit f5bde9b79394a6bf61b6b9daefc36ceaa84b82be.

* subxt: Perform RuntimeVersion update before fetching metadata

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Reintroduce MetadataInner

* Use parking lot instead of std::RwLock

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Reduce lock metadata time when decoding events

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Update `validate_metdata` locking pattern

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt/examples: Update polkadot download link

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* tests: Wrap metadata in a helper function

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update examples/examples/subscribe_runtime_updates.rs

Co-authored-by: James Wilson <james@jsdw.me>

* subxt/updates: Update runtime if version is different

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

Co-authored-by: James Wilson <james@jsdw.me>

codegen/src/api/constants.rs

@@ -49,8 +49,10 @@ pub fn generate_constants(
         quote! {
             #( #[doc = #docs ] )*
             pub fn #fn_name(&self) -> ::core::result::Result<#return_ty, ::subxt::BasicError> {
-                if self.client.metadata().constant_hash(#pallet_name, #constant_name)? == [#(#constant_hash,)*] {
-                    let pallet = self.client.metadata().pallet(#pallet_name)?;
+                let locked_metadata = self.client.metadata();
+                let metadata = locked_metadata.read();
+                if metadata.constant_hash(#pallet_name, #constant_name)? == [#(#constant_hash,)*] {
+                    let pallet = metadata.pallet(#pallet_name)?;
                     let constant = pallet.constant(#constant_name)?;
                     let value = ::subxt::codec::Decode::decode(&mut &constant.value[..])?;
                     Ok(value)