Added an environment to control if Firehoe is preferred or not when present (#3166)

chain/ethereum: added an environment to control if Firehoe is preferred or not when present

If the environment is **not** set, the current behavior and Firehose is automatically picked up if there is endpoints configured with it.

If the environment set, firehose is preferred only if the variable is true and there is endpoints configured with it.

Author: Matthieu Vachon

chain/ethereum/src/chain.rs

@@ -2,6 +2,7 @@ use anyhow::{Context, Error};
 use graph::blockchain::BlockchainKind;
 use graph::components::store::WritableStore;
 use graph::data::subgraph::UnifiedMappingApiVersion;
+use graph::env::env_var;
 use graph::firehose::{FirehoseEndpoints, ForkStep};
 use graph::prelude::{
     EthereumBlock, EthereumCallCache, LightEthereumBlock, LightEthereumBlockExt, StopwatchMetrics,
@@ -48,16 +49,14 @@ use graph::blockchain::block_stream::{BlockStream, FirehoseCursor};
 
 lazy_static! {
     /// Maximum number of blocks to request in each chunk.
-    static ref MAX_BLOCK_RANGE_SIZE: BlockNumber = std::env::var("GRAPH_ETHEREUM_MAX_BLOCK_RANGE_SIZE")
-        .unwrap_or("2000".into())
-        .parse::<BlockNumber>()
-        .expect("invalid GRAPH_ETHEREUM_MAX_BLOCK_RANGE_SIZE");
+    static ref MAX_BLOCK_RANGE_SIZE: BlockNumber = env_var("GRAPH_ETHEREUM_MAX_BLOCK_RANGE_SIZE", 2000);
 
     /// Ideal number of triggers in a range. The range size will adapt to try to meet this.
-    static ref TARGET_TRIGGERS_PER_BLOCK_RANGE: u64 = std::env::var("GRAPH_ETHEREUM_TARGET_TRIGGERS_PER_BLOCK_RANGE")
-        .unwrap_or("100".into())
-        .parse::<u64>()
-        .expect("invalid GRAPH_ETHEREUM_TARGET_TRIGGERS_PER_BLOCK_RANGE");
+    static ref TARGET_TRIGGERS_PER_BLOCK_RANGE: u64 = env_var("GRAPH_ETHEREUM_TARGET_TRIGGERS_PER_BLOCK_RANGE", 100);
+
+    /// Controls if firehose should be preferred over RPC if Firehose endpoints are present, if not set, the default behavior is
+    /// is kept which is to automatically favor Firehose.
+    static ref IS_FIREHOSE_PREFERRED: bool = env_var("GRAPH_ETHEREUM_IS_FIREHOSE_PREFERRED", true);
 }
 
 /// Celo Mainnet: 42220, Testnet Alfajores: 44787, Testnet Baklava: 62320
@@ -319,7 +318,7 @@ impl Blockchain for Chain {
     }
 
     fn is_firehose_supported(&self) -> bool {
-        self.firehose_endpoints.len() > 0
+        *IS_FIREHOSE_PREFERRED && self.firehose_endpoints.len() > 0
     }
 }