Add getBlockTime rpc api (#7130)

* Add getBlockTime rpc api

* Add getBlockTime to docs

* Fix duration rounding for common tick/slot durations; add slot duration calculation

* Expose slots_per_year

* Use genesis values instead of clock defaults to calculate block offset

* Add get-block-time cli subcommand

* Fix test_rent: decrease magic number usage

client/src/rpc_client.rs

@@ -11,7 +11,7 @@ use log::*;
 use serde_json::{json, Value};
 use solana_sdk::{
     account::Account,
-    clock::{Slot, DEFAULT_TICKS_PER_SECOND, DEFAULT_TICKS_PER_SLOT},
+    clock::{Slot, UnixTimestamp, DEFAULT_TICKS_PER_SECOND, DEFAULT_TICKS_PER_SLOT},
     commitment_config::CommitmentConfig,
     epoch_schedule::EpochSchedule,
     fee_calculator::FeeCalculator,
@@ -196,6 +196,32 @@ impl RpcClient {
         })
     }
 
+    pub fn get_block_time(&self, slot: Slot) -> io::Result<UnixTimestamp> {
+        let params = json!(slot);
+        let response = self
+            .client
+            .send(&RpcRequest::GetBlockTime, Some(params), 0, None);
+
+        response
+            .map(|result_json| {
+                if result_json.is_null() {
+                    return Err(io::Error::new(
+                        io::ErrorKind::Other,
+                        format!("Block Not Found: slot={}", slot),
+                    ));
+                }
+                let result = serde_json::from_value(result_json)?;
+                trace!("Response block timestamp {:?} {:?}", slot, result);
+                Ok(result)
+            })
+            .map_err(|err| {
+                io::Error::new(
+                    io::ErrorKind::Other,
+                    format!("GetBlockTime request failure: {:?}", err),
+                )
+            })?
+    }
+
     pub fn get_epoch_info(&self) -> io::Result<RpcEpochInfo> {
         self.get_epoch_info_with_commitment(CommitmentConfig::default())
     }

client/src/rpc_request.rs

@@ -111,6 +111,7 @@ pub enum RpcRequest {
     ValidatorExit,
     GetAccountInfo,
     GetBalance,
+    GetBlockTime,
     GetClusterNodes,
     GetEpochInfo,
     GetEpochSchedule,
@@ -150,6 +151,7 @@ impl RpcRequest {
             RpcRequest::ValidatorExit => "validatorExit",
             RpcRequest::GetAccountInfo => "getAccountInfo",
             RpcRequest::GetBalance => "getBalance",
+            RpcRequest::GetBlockTime => "getBlockTime",
             RpcRequest::GetClusterNodes => "getClusterNodes",
             RpcRequest::GetEpochInfo => "getEpochInfo",
             RpcRequest::GetEpochSchedule => "getEpochSchedule",