Implement tree explain for LazyMemoryExec (#15187)

Resolve conflicts

Author: zebsme

datafusion/physical-plan/src/memory.rs

@@ -193,8 +193,17 @@ impl DisplayAs for LazyMemoryExec {
                 )
             }
             DisplayFormatType::TreeRender => {
-                // TODO: collect info
-                write!(f, "")
+                //TODO: remove batch_size, add one line per generator
+                writeln!(
+                    f,
+                    "batch_generators={}",
+                    self.batch_generators
+                        .iter()
+                        .map(|g| g.read().to_string())
+                        .collect::<Vec<String>>()
+                        .join(", ")
+                )?;
+                Ok(())
             }
         }
     }

datafusion/sqllogictest/test_files/explain_tree.slt

@@ -725,7 +725,12 @@ physical_plan
 32)└─────────────┬─────────────┘
 33)┌─────────────┴─────────────┐
 34)│       LazyMemoryExec      │
-35)└───────────────────────────┘
+35)│    --------------------   │
+36)│     batch_generators:     │
+37)│ generate_series: start=1, │
+38)│    end=1000, batch_size   │
+39)│           =8192           │
+40)└───────────────────────────┘
 
 query TT
 explain select 
@@ -1641,3 +1646,16 @@ physical_plan
 08)│       format: memory      │
 09)│          rows: 1          │
 10)└───────────────────────────┘
+
+# Test explain tree for LazyMemoryExec
+query TT
+EXPLAIN SELECT * FROM generate_series(1, 100)
+----
+physical_plan
+01)┌───────────────────────────┐
+02)│       LazyMemoryExec      │
+03)│    --------------------   │
+04)│     batch_generators:     │
+05)│ generate_series: start=1, │
+06)│  end=100, batch_size=8192 │
+07)└───────────────────────────┘